511 research outputs found
Epitaxially strained ultrathin LaNiO/LaAlO and LaNiO/SrTiO superlattices: a density functional theory + study
By employing first-principles electronic structure calculations we
investigate nickelate superlattices [LaNiO]/[LaAlO] and
[LaNiO]/[SrTiO] with (001) orientation under epitaxial tensile
strain. Within density functional theory augmented by mean-field treatement of
on-site electronic correlations, the ground states show remarkable dependence
on the correlation strength and the strain. In the weakly and intermediately
correlated regimes with small epitaxial strain, the charge-disproportionated
insulating states with antiferromagneitc order is favored over the other
orbital and spin ordered phases. On the other hand, in the strongly correlated
regime or under the large tensile strain, ferromagnetic spin states with
Jahn-Teller orbital order become most stable. The effect from polar interfaces
in LaNiO]/[SrTiO] is found to be noticeable in our
single-layered geometry. Detailed discussion is presented in comparison with
previous experimental and theoretical studies.Comment: 9 pages, 8 figure
Intangible assets investment and firms’ performance: evidence from small and medium-sized enterprises in Korea
While many studies have examined the relationship between investment in intangibles assets and performance in large corporations, current research is lacking in regard to intangible investments in small and medium enterprises (SMEs). This study looks at SMEs in which intangible investments would usually be minor because they tend to consider intangible investment as an inefficient cost and concentrate on investments in tangible assets. This paper aims to contribute to the current literature and suggests that investment in the intangible assets of (human capital, advertising, R&D) is essential for SMEs pursuing superior firm performance. Actual data collected from 173 SMEs in Korea were analyzed employing hierarchical regression methodology. Results indicate that all three intangible resources have a positive effect on a firm’s profitability and value. Interestingly, this research finds that investment in advertising has the most influential impact on a firm’s profitability and value. This study has implications for SMEs in achieving their profitability and value. The results in this study highlight that intangible investment is not a waste of money for SMEs, and that business managers could strategically utilize these three key contributors (human capital, advertising, R&D) and adopt investment in intangible assets to accomplish their managerial goals
On the origin of the hump structure in the in-plane optical conductivity of high Tc cuprates based on a SU(2) slave-boson theory
An improved version of SU(2) slave-boson approach is applied to study the
in-plane optical conductivity of the two dimensional systems of high Tc
cuprates. We investigate the role of fluctuations of both the phase and
amplitude of order parameters on the (Drude) peak-dip-hump structure in the
in-plane conductivity as a function of hole doping concentration and
temperature. The mid-infrared(MIR) hump in the in-plane optical conductivity is
shown to originate from the antiferromagnetic spin fluctuations of short
range(the amplitude fluctuations of spin singlet pairing order parameters),
which is consistent with our previous U(1) study. However the inclusion of both
the phase and amplitude fluctuations is shown to substantially improve the
qualitative feature of the optical conductivity by showing substantially
reduced Drude peak widths for entire doping range. Both the shift of the hump
position to lower frequency and the growth of the hump peak height with
increasing hole concentration is shown to be consistent with observations.Comment: 7 pages, 6 figure
Enhancing spectral contrast in organic red-light photodetectors based on a light-absorbing and exciton-blocking layered system
This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in JOURNAL OF APPLIED PHYSICS. 108(3):034502 (2010) and may be found at https://doi.org/10.1063/1.3466766 .We demonstrated a highly sensitive red-light photodetector based on a mixed copper phthalocyanine (CuPc) and fullerene C-60 photoactive layer, similar to a so-called bulk heterojunction structure usually used in the field of organic photovoltaics. We incorporated an additional set of organic layers that was composed of two organic p-type semiconductors to reduce the blue-light sensitivities of CuPc- and C-60-based organic photodetectors. We used alpha, omega-diphenyl sexi-thiophene (P6T) and alpha, omega-bis(biphenyl-4-yl)ter-thiophene (BP3T), which are thiophene-based materials and usually have good hole-transporting properties. A thick (>100 nm) P6T layer absorbed blue light, preventing it from reaching the photoactive layer, and a thin (similar to 20 nm) BP3T layer whose band gap was larger than that of P6T blocked excitation energy transfer from P6T to CuPc. Thus, we successfully demonstrated a red-light photodetector with high peak sensitivity and whose current-voltage characteristics did not worsen. The optimal device showed a peak incident photon-current conversion efficiency of 51.7% at 620 nm and a specific detectivity of 4.0 X 10(11) cm Hz(1/2)/W.ArticleJOURNAL OF APPLIED PHYSICS. 108(3):034502 (2010)journal articl
Normal stress difference-driven particle focusing in nanoparticle colloidal dispersion
Colloidal dispersion has elastic properties due to Brownian relaxation process. However, experimental evidence for the elastic properties, characterized with normal stress differences, is elusive in shearing colloidal dispersion, particularly at low Peclet numbers (Pe < 1). Here, we report that single micrometer-sized polystyrene (PS) beads, suspended in silica nanoparticle dispersion (8 nm radius; 22%, v/v), laterally migrate and form a tightly focused stream by the normal stress differences, generated in pressure-driven microtube flow at low Pe. The nanoparticle dispersion was expected to behave as a Newtonian fluid because of its ultrashort relaxation time (2 mu s), but large shear strain experienced by the PS beads causes the notable non-Newtonian behavior. We demonstrate that the unique rheological properties of the nanoparticle dispersion generate the secondary flow in perpendicular to mainstream in a noncircular conduit, and the elastic properties of blood plasma-constituting protein solutions are elucidated by the colloidal dynamics of protein molecules
Metastasis of Transitional Cell Carcinoma to the Lower Abdominal Wall 20 Years after Cystectomy
Iatrogenic implantation has been the main cause in the majority of cases of transitional call carcinoma (TCC) with metastasis to the abdominal wall. A 66-year-old woman had undergone radical cystectomy 20 years prior to presenting. Radiological investigations revealed one mass in the left lower abdominal wall and one mass in the right inguinal area. She underwent wide excision of the lesions that revealed metastasis of TCC. This report describes this case of a woman with bladder carcinoma who developed a metastasis in the anterior abdominal wall following an apparent disease-free interval of 20 years
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