241 research outputs found
Erratum to: Comparative Studies of the Growth and Characterization of Germanium Epitaxial Film on Silicon (001) with 0° and 6° Offcut
In the original article we presented results that show that the strain in germanium (Ge) epitaxial films grown directly on a silicon (Si) (001) with 6° offcut has a tensile strain of 0.6%. This strain value is much higher than the typical tensile strain value of 0.2% reported for Ge/Si. This discrepancy is due unintentional omission of the Si offcut angle and azimuth angle (φ) of the sample during high-resolution x-ray diffraction (HRXRD) measurement, and it has unfortunately resulted in a misleading result
The theoretical direct-band-gap optical gain of Germanium nanowires
We calculate the electronic structures of Germanium nanowires by taking the
effective-mass theory. The electron and hole states at the G-valley are studied
via the eight-band k.p theory. For the [111] L-valley, we expand the envelope
wave function using Bessel functions to calculate the energies of the electron
states for the first time. The results show that the energy dispersion curves
of electron states at the L-valley are almost parabolic irrespective of the
radius of Germanium nanowires. Based on the electronic structures, the density
of states of Germanium nanowires are also obtained, and we find that the
conduction band density of states mostly come from the electron states at the
L-valley because of the eight equivalent degenerate L points in Germanium.
Furthermore, the optical gain spectra of Germanium nanowires are investigated.
The calculations show that there are no optical gain along z direction even
though the injected carrier density is 4x1019 cm-3 when the doping
concentration is zero, and a remarkable optical gain can be obtained when the
injected carrier density is close to 1x1020 cm-3, since a large amount of
electrons will prefer to occupy the low-energy L-valley. In this case, the
negative optical gain will be encountered considering free-carrier absorption
loss as the increase of the diameter. We also investigate the optical gain
along z direction as functions of the doping concentration and injected carrier
density for the doped Germanium nanowires. When taking into account
free-carrier absorption loss, the calculated results show that a positive net
peak gain is most likely to occur in the heavily doped nanowires with smaller
diameters. Our theoretical studies are valuable in providing a guidance for the
applications of Germanium nanowires in the field of microelectronics and
optoelectronics
Unveiling the practices and challenges of professional learning community in a Malaysia Chinese School
Professional learning community (PLC) studies in the Asian Chinese nations remain scarce despite the emerging interest in the practice of PLC beyond the Western context. This study attempts to provide an understanding of the practices of PLC and challenges in implementing PLC in a Malaysian Chinese culture–dominated secondary school. This qualitative study used a phenomenological constructivist approach as a strategy of inquiry. Semi-structured interview data were collected from six middle leaders and ordinary teachers in a national-type Chinese secondary school in the northern region. Findings informed three existing PLC practices at the school level, namely, (a) peer coaching, (b) sharing of personal practices, and (c) professional development courses. However, the practice of PLC encounters various challenges, including excessive workload, teachers’ passive attitudes, unsupportive conditions in the school, poor execution of PLC by the school community, and a vague understanding of PLC. Interestingly, this study identified two uncovered challenges hindering the development of PLC: misconception about PLC and lack of supervision from the authority. Implications and future studies are presented
Unveiling the practices and challenges of professional learning community in a Malaysian Chinese Secondary School
Professional learning community (PLC) studies in the Asian Chinese nations remain scarce despite the emerging interest in the practice of PLC beyond the Western context. This study attempts to provide an understanding of the practices of PLC and challenges in implementing PLC in a Malaysian Chinese culture–dominated secondary school. This qualitative study used a phenomenological constructivist approach as a strategy of inquiry. Semi-structured interview data were collected from six middle leaders and ordinary teachers in a national-type Chinese secondary school in the northern region. Findings informed three existing PLC practices at the school level, namely, (a) peer coaching, (b) sharing of personal practices, and (c) professional development courses. However, the practice of PLC encounters various challenges, including excessive workload, teachers’ passive attitudes, unsupportive conditions in the school, poor execution of PLC by the school community, and a vague understanding of PLC. Interestingly, this study identified two uncovered challenges hindering the development of PLC: misconception about PLC and lack of supervision from the authority. Implications and future studies are presented
Unveiling the Practices and Challenges of Professional Learning Community in a Malaysian Chinese Secondary School
Professional learning community (PLC) studies in the Asian Chinese nations remain scarce despite the
emerging interest in the practice of PLC beyond the Western context. This study attempts to provide an
understanding of the practices of PLC and challenges in implementing PLC in a Malaysian Chinese culture–
dominated secondary school. This qualitative study used a phenomenological constructivist approach as a
strategy of inquiry. Semi-structured interview data were collected from six middle leaders and ordinary
teachers in a national-type Chinese secondary school in the northern region. Findings informed three
existing PLC practices at the school level, namely, (a) peer coaching, (b) sharing of personal practices, and
(c) professional development courses. However, the practice of PLC encounters various challenges,
including excessive workload, teachers’ passive attitudes, unsupportive conditions in the school, poor
execution of PLC by the school community, and a vague understanding of PLC. Interestingly, this study
identified two uncovered challenges hindering the development of PLC: misconception about PLC and lack
of supervision from the authority. Implications and future studies are presented
Quantitation of green fluorescent protein using a gel-based imaging method.
Green fluorescent protein (GFP) is a versatile reporter protein and has been widely used in biological research. However, its quantitation requires expensive equipment such as a spectrofluorometer. In the current study, a gel documentation imaging system using a native polyacrylamide gel for the quantitation of GFP was developed. The assay was evaluated for its precision, linearity, reproducibility, and sensitivity in the presence of Escherichia coli cells and was compared with the spectrofluorometric method. Using this newly established, gel-based imaging technique; the amount of GFP can be quantified accurately
Secondary Household Transmission of SARS, Singapore
Secondary household transmission of severe acute respiratory syndrome (SARS) was studied in 114 households involving 417 contacts. The attack rate was low (6.2%). Occupation of the index case was the factor that most influenced household transmission (adjusted hazard ratio for healthcare workers 0.157; 95% confidence interval 0.042 to 0.588)
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