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81.
Janet Tassell Natasha E. Gerstenschlager Toni Syzmanski Savannah Denning 《School science and mathematics》2020,120(6):333-344
Innovation is more imperative now than ever before given the upcoming shortage in prepared teachers and the need to produce students with a strong knowledge of mathematics. A sense of urgency is impacting teacher education/preparation programs as instructional practices need to discover how to arm teachers to increase the number of students to be not only college-ready but also desiring to pursue Science, Technology, Engineering, and Mathematics majors. As such, the purpose of this study, was to determine how the four variables (mindfulness, mathematics anxiety, self-efficacy, and mindset) are interconnected within preservice elementary teachers (PSETs), and how we as teacher educators can better address these variables within our own PSETs. Each semester included three seminars with similar overall foci including the four variables. Participants in this study were recruited from Elementary Education students at an east south central regional university enrolled in a mathematics methods course. Thirty-seven participants were divided into control (N = 20) and treatment (N = 17). In this article, we present both qualitative and quantitative results from our mixed-methods study that considered these questions. With the results of this study revealing an inter-connectedness among the four variables, this research further informs the teacher educator community. 相似文献
82.
M. Galceran M. C. Pujol M. Aguiló F. Díaz 《Journal of Sol-Gel Science and Technology》2007,42(1):79-88
KRE(WO4)2 (RE = Gd and Yb) nanocrystalline powder was obtained by the modified sol-gel Pechini method. The precursor powder was calcined
between 923 and 1023 K for a maximum of 6 h at air atmosphere. DTA-TG of the precursor powder shows that the temperature for
total calcination is around 800–850 K. Molar ratio between the complexing agent and the metal ions in the first step of the
method and molar ratio between the complexing agent and the ethylene glycol in the second step of the method were studied
to optimize the preparation process. X-ray diffraction and IR spectroscopy were used to study the transformation from precursor
powder into a crystalline monoclinic phase. Raman spectroscopy was used to study the vibrational structure of the nanoparticles.
The Scherrer formula was used to confirm the grain sizes visualized by SEM and TEM techniques. Small nanoparticles in the
range of 20–50 nm of monoclinic KREW have been successfully obtained by this methodology. 相似文献
83.
Optimisation of liquid scintillation counting conditions for rapid tritium determination in aqueous samples 总被引:1,自引:0,他引:1
Ll. Pujol J. A. Sanchez-Cabeza 《Journal of Radioanalytical and Nuclear Chemistry》1999,242(2):391-398
Several studies were carried out to optimise rapid tritium analysis in fresh waters by ultra-low background liquid scintillation.
These included the optimisation of (1) sample/scintillant ratio, (2) pulse shape analysis, and (3) pulse-amplitude comparator,
and studies concerning (1) the combination scintillant/vial and (2) the effect of chemiluminescence. The proposed method involves
the mixing of 8 ml sample with 12 ml scintillation cocktail Ultima Gold AB in Zinsser low diffusion vials. These are stored
during one day before counting in order to reduce chemiluminescence. The minimum detectable activity achieved was 2.2 Bq·l−1 for a total counting time of 360 minutes. In order to test the method, tritium was determined in Ebro river samples. 相似文献
84.
The synthesis and chemical trapping of a highly pyramidalized pentacyclo[6.4.0.0(2,10).0(3,7).0(4,9)]dodec-8-ene containing ketal functions is reported. Its cross-coupling reaction with 3, 7-dimethyltricyclo[3.3.0.0(3,7)]oct-1(5)-ene followed by a [2 + 2] retrocycloaddition reaction gives a straightforward access to functionalized tetrasecododecahedradienes. 相似文献
85.
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87.
5,8-Isoquinolinedione was synthesized from 5-hydroxyisoquinoline by nitrosation at C-8, reduction of the nitroso group and oxidation of the resultant 5-hydroxy-8-aminoisoquinoline. 相似文献
88.
89.
V. Jambunathan X. Mateos M. C. Pujol J. J. Carvajal C. Zaldo U. Griebner V. Petrov M. Aguiló F. Díaz 《Applied physics. B, Lasers and optics》2014,116(2):455-466
We present the crystal growth, optical spectroscopy, and room temperature continuous-wave (CW) laser operation of monoclinic Ho:KLu(WO4)2 crystals. Macro defect-free crystals of several dopant concentrations were grown by top-seeded solution growth slow-cooling method. The evolution of unit cell parameters with holmium doping level and temperature was studied using X-ray powder diffraction. The spectroscopic properties were characterized in terms of room- and low-temperature optical absorption and photoluminescence. From low-temperature optical absorption measurements, the energy of the Stark levels was determined. Calculation of the emission and gain cross sections is presented. CW laser action was realized for 3 and 5 at. % Ho-doped KLu(WO4)2 by in-band pumping using a Tm:KLu(WO4)2 pump laser. A maximum output power of 507 mW with a slope efficiency of ~38 % with respect to the incident power was achieved at 2,080 nm with the Ho:KLu(WO4)2 laser. 相似文献
90.