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The internal capital adequacy and assessment process (ICAAP) was first introduced in the second pillar of Basel II in 2004 to offset the deficiencies of Basel I and capital adequacy regulations in the first pillar of Basel II. This process is aimed at identifying and measuring risks generated in banks’ activities, and then provides the requirements for internal capital levels and methods to raise capital to deal with these risks. In fact, the implementation of Basel II and ICAAP in Vietnamese commercial banks has attained notable achievements, but it also revealed some major weaknesses. The purpose of this research is to evaluate the implementation of ICAAP in Vietnamese commercial banks in eight components of the ICAAP addressed by Basel II using the survey method and then to simulate the implementation of ICAAP in a Vietnamese commercial bank. From the facts and the simulation of the ICAAP framework in this study, the authors offer some suggestions for Vietnamese commercial banks to implement ICAAP effectively in their banking operations.

International audience; Recently, treatment advances in direct-acting antivirals have radically changed the management of HCV patients. However, in resource-limited countries, identification of patients with active HCV infection is still challenging in remote settings due to the limited access to laboratories able to measure HCV viral load. This study evaluated whether dried blood spots (DBS) transferred to a central laboratory could overcome this challenge. A total of 315 HCV-infected patients, naïve to anti-HCV treatment, provided each three type of samples: plasma, DBS with calibrated quantities of venous blood and DBS with uncalibrated quantities of capillary blood. Qualitative comparison was conducted in terms of detection of HCV viral load on DBS as opposed to plasma to estimate sensitivity and specificity. Quantitative comparisons were conducted by means of correlation estimation. Of the 250 patients with detected plasma HCV viral load, 245 also had detectable DBS HCV viral load (capillary or venous) leading to a sensitivity of 98.0% (95% confidence interval (CI): 95.4%-99.3%); importantly, all measurements with a plasma HCV viral load >118 IU/mL were also detected in DBS. When HCV was not detected in plasma, it was also not detected in DBS resulting in 100% specificity (95% CI: 94.5%-100%). Quantitative HCV viral load results were very similar when utilizing plasma or DBS sample types as illustrated by correlations >0.99. In conclusion, DBS sample types, with either uncalibrated capillary blood or calibrated venous blood, performed well to distinguish patients with active HCV infection, and who therefore need treatment, from other patients.

The long stagnation of the photo-conversion efficiency of kesterites below 13% is a source of frustration in the scientific community. In this study, we investigated the effects of sodium on the passivation of grain boundaries and defects in Cu2ZnSnSe4 (CZTSe) grown on a soda-lime glass (SLG) and borosilicate (BS) glass. Because BS glass does not inherently contain sodium, we placed a thin layer of NaF between CZTSe and Mo. The composition of the samples is Cu-poor and Zn-rich. The distribution of sodium and its contributions to phase formation and defects were examined by cross-sectional energy-dispersive X-ray profiling, Raman scattering spectroscopy and imaging, surface potential and photoluminescence. From the experimental results, it can be strongly claimed that sodium ions segregate predominantly near the grain boundaries and reduce CuZn-related defects. These local surface imaging analyses provided the exact locations of the secondary phases. In particular, the photo-assisted scanning probe method enabled us to observe the changes in the optoelectrical properties of the thin films and the carrier behavior within the materials. Further studies with distinct alkali ions and optimal processing conditions will pave a way to improve the performance of kesterite solar cells.

Background Patient-prosthesis mismatch (PPM) is a major concern in aortic valve replacement (AVR) and leads to perioperative morbidity and rehospitalization. Predicting aortic annulus diameter pre-procedurally is crucial to managing patients with high-risk of PPM. Objectives To compare preoperative measurements of aortic annulus from echocardiography and CT scan with surgical sizing and develop an imaging-based algorithm to predict PPM. Methods From January 2017 to December 2020, patients underwent AVR at a teaching hospital were examined. The relationship between imaging measurements with operative values was assesed using scatter plots and Pearson’s correlation coefficient. Univariable linear regression was then used to build the predictive model. Results A total of 144 patients underwent AVR during the study period. Suture types and surgical approaches were not significantly associated with prosthesis size. CT scan-based measurements showed strong correlation with prosthesis size: mean diameter (R = 0.79), perimeter-derived diameter (R = 0.76), and area-derived diameter (R = 0.75). Mechanical valve and tissue valve shared similar correlation coefficients. Prosthesis size predictive models based on CT scan were 12.89 + 0.335 × d for mean diameter, 13.275 + 0.315 × d for perimeter-derived diameter and 13.626 + 0.309 × d for area-derived diameter. Conclusions Preoperative CT scan measurements are a reliable predictor of aortic prosthesis size. Transthoracic echocardiography is a possible alternative, though it is highly performer-dependent and unable to represent the aortic annulus fully. Together, these two imaging modalities can be used to quantitatively anticipate PPM preoperatively.

Heterostructures enable the control of transport and recombination of charge carriers, which are either injected through electrodes, or created by light illumination. Instead of full 2D-material-heterostructures in device applications, using hybrid heterostructures consisting of 2D and 3D materials is an alternative approach to take advantage of the unique physical properties of 2D materials. In addition, 3D dielectric nanostructures exhibit useful optical properties such as broadband omnidirectional antireflection effects and strongly concentrated light near the surface. In this work, the optical properties of 2D MoS2 monolayers conformally coated on 3D Si-based nanocone (NC) arrays are investigated. Numerical calculations show that the absorption in MoS2 monolayers on SiO2 NC is significantly enhanced, compared with that for MoS2 monolayers on Si NC. The weak light confinement in low refractive index SiO2 NC leads to greater absorption in the MoS2 monolayers. The measured photoluminescence and Raman intensities of the MoS2 monolayers on SiO2 NC are much greater than those on Si NC, which supports the calculation results. This work demonstrates that 2D MoS2-3D Si nano-heterostructures are promising candidates for use in high-performance integrated optoelectronic device applications.

Hybrid lead halide perovskite possesses attractive properties and outstanding performance. The electronic structure of hybrid lead halide perovskite single crystal can be used to comprehend its intrinsic properties. In this study, the crystal structure of CH3NH3PbBr3 perovskite crystal was elucidated by transmission electron microscopy. Phonon modes and CH3NH3+ rocking modes were analyzed. Band gaps of the crystal were obtained by temperature-dependent Raman scattering spectroscopy and photoluminescence measurement. Surface potential measurement for a (001) plane exhibited a work function of the material and other phases of PbBr2 and CH3NH3Br. From experimentally determined values, an electronic structure of CH3NH3PbBr3 was built. It showed a p-type characteristic.

There has been growing research interest in realizing optoelectronic devices based on the two-dimensional atomically thin semiconductor MoS2 owing to its distinct physical properties that set it apart from conventional semiconductors. However, there is little optical absorption in these extremely thin MoS2 layers, which presents an obstacle toward applying them for use in high-efficiency light-absorbing devices. We synthesized trilayers of MoS2 directly on SiO2/Si nanocone (NC) arrays using chemical vapor deposition and investigated their photodetection characteristics. The photoresponsivity of the MoS2/NC structure was much higher than that of the flat counterpart across the whole visible wavelength range (for example, it was almost an order of magnitude higher at λ = 532 nm). Strongly concentrated light near the surface that originated from a Fabry–Perot interference in the SiO2 thin layers and a Mie-like resonance caused by the Si NCs boosted the optical absorption in MoS2. Our work demonstrates that M...

CH3NH3PbCl3 (MAPbCl3) perovskite single crystal is attractive for the ultra-violet detector due to its wide bandgap and comparative stability over iodine or bromine systems. Single crystals of MAPbCl3 perovskite are also intriguing owing to its generic type of materials for fundamental photophysical properties and excitonic behaviors for its use in devices. Furthermore, recent progress using crystal-based device fabrication will shed light on semiconducting devices like III–V compounds. In this study, a structurally well-defined crystal is grown and examined to reveal free and bound excitonic behaviors depending on the structural phase transition. We classified the free and bound excitonic behaviors by temperature- and power density-dependent photoluminescence and optical transmission spectra. The single emission peak located at 3.1 eV and blueshift depending on decreasing the temperature is attributed to the radiative recombination of the free exciton at the cubic and the tetragonal phases, whereas the several peaks from the bound excitonic transition are just revealed under 120 K of the orthorhombic phase. We also determined the work function distribution and band structures with excitonic bound states via Kelvin probe force microscopy. The optoelectronic properties resulted in the excitonic behaviors can be a fundamental approach for the construction of perovskite-based optoelectronic and photonic applications.

The use of an indium surfactant considerably alters the composition and morphology of low-temperature non-polar m-plane ( 10 1 ¯ 0 ) AlxGa1−xN (x ∼ 0.2) and of silicon-doped AlGaN/InGaN multiple quantum wells grown by plasma-assisted molecular beam epitaxy. This paper compares heterostructures grown with indium surfactant with those grown under conventional stoichiometric and gallium-rich conditions at the relatively low temperature necessary for growth of In0.16Ga0.84N quantum wells (565 °C). Stoichiometric growth results in rough, inhomogeneous AlGaN layers that are unsuitable for optical devices. Gallium-rich growth produces a smoother AlGaN layer, reduced inhomogeneities, and sharper interfaces as compared to stoichiometric growth. However, due to the low temperature, gallium-rich growth leads to the formation of an unintentional GaN layer on top of each AlGaN barrier, reducing the energies of confined electronic states in the quantum wells. An indium surfactant enables two-dimensional AlGaN growth at low temperature, producing atomically flat surface morphology and sharp heterostructure interfaces. Indium surfactant assisted epitaxy also eliminates the high aluminum alloy inhomogeneities observed with conventional stoichiometric and gallium-rich growth. Even though partial indium incorporation into the AlGaN layer is found at the studied temperatures, the high-quality, uniform non-polar In0.055Al0.19Ga0.755N/In0.16Ga0.84N quantum wells grown with indium surfactant display bright and narrow photoluminescence that is essential for device applications.

MoS2, a representative 2D atomically thin semiconductor, has a sizable band gap leading to intensive research efforts to investigate its unique optical properties and realize a novel optoelectronic device based on MoS2. However, limited optical absorption in extremely thin MoS2 layers is an obstacle for high-efficiency light absorbing devices. In this work, we investigated how reflection and transmission phase-shift at the highly absorbing MoS2 interface could affect the absorption spectra of the MoS2 monolayers on SiO2/Si substrates (SiO2 thickness: 40 ~ 130 nm). Such interface-phase-shift gave rise to interference in MoS2 layer, although the layer thickness was only 0.7 nm, much smaller than the wavelength of the visible light. We compared measured and calculated optical reflection spectra, which showed that aforementioned interface-interference enhanced optical absorption in MoS2 monolayers. Raman intensity of MoS2 monolayers largely varied depending on the SiO2 thickness, which could be well explained by the calculated absorption in MoS2 layers. In addition, the interface-interference enabled omnidirectional absorption enhancement. This work showed that proper choice of the SiO2 thickness could provide us a simple and useful means to improve optical absorption in MoS2 monolayers.

We used X-ray diffraction (XRD) and Raman scattering spectroscopy to study Cu2ZnSnS4 (CZTS) thin films grown by using an electroplating method. We compared the Raman spectra of the CZTS thin films before and after potassium cyanide (KCN) etching. We observed a phonon mode of the secondary phase Cu2−x S both from Cu-rich and Cu-poor CZTS samples before the KCN etching. We found that the intensity of the Cu2−x S-related vibration mode depended on the excitation wavelength, from which we could estimate the stoichiometry of the Cu2−x S as x = 1. Interestingly, the Cu2−x S phonon is completely removed after the KCN etching. We could also get information regarding the local distribution of the secondary phase on the surfaces of the CZTS thin films by using micro-Raman scattering spectroscopy.