Photoluminescence from Si nanocrystals exposed to a hydrogen plasma

Si nanocrystals embedded in SiO₂films were exposed to an atomic H plasma at different temperatures. Photoluminescence intensity from the nanocrystals increases with increasing exposure time, followed by saturation that depends on the exposure temperature. The saturation level depends on the final exposure temperature and shows no dependence on the thermal history of exposure. This behavior is shown to be consistent with a model in which the steady-state passivation level is determined by a balance between defect passivation and depassivation by H, with the activation energy for the passivationreaction being larger than that for the depassivation reaction.This work was supported by Research Institute for Basic Science at Kangwon National University

Direct growth of nickel disilicide nanocrystals in silicon dioxide films

Nickel disilicide (NiS₂)nanocrystals (NCs) have been grown in silicon-rich oxide (SiOₓ)films ion implanted with nickel by annealing at 1100°C. It was found that NiS₂ NCs grew into well-defined single crystalline structures embedded in a SiOₓ matrix and were approximately spherical in shape. The size of NCs can be influenced by limiting either the Ni or excess Si concentration. It was found that the resulting NCs could be produced with diameters in the range from 5to40nm in the SiOₓ layers with excess Si concentrations of 4–8at.% implanted with Ni concentrations of 0.1–10at.%.This work was carried out under Scientists Exchange Program between the Korea Science and Engineering Foundation and the Australian Academy of Science, and supported by the Research Grant from the Kangwon National University

Formation of nickel-based nanocrystal monolayers for nonvolatile memory applications

A simple method for fabricating metal silicide nanocrystal layers with narrow spatial distributions is demonstrated and shown to produce structures suitable for nonvolatile memory applications. The method is based on high-temperature annealing of a sandwich structure comprised of a thin metal (Ni)film sandwiched between two silicon-rich oxide (SiOₓ) layers and has the feature in which the size of the NCs can be controlled by varying the silicon concentrations in the SiOₓ layers or the initial nickelfilm thickness. The typical nanocrystal diameters and densities are 3.6nm and 1.2×10¹²cm⁻², respectively. Capacitance-voltage (C-V) measurements on test structures with these characteristics are shown to have C-V characteristics suitable for nonvolatile memory applications, including a C-V memory window of 11.7V for sweep voltages between −12V and +12.This work was supported by the Korea Research Foundation Grant funded by the Korean Government MOEHRD, KRF-2007-313-C00269 and by the Australian Research Council through its Discovery Grant Program

Expression of matrix metalloproteinases to induce the expression of genes associated with apoptosis during corpus luteum development in bovine

Here we investigated the expressions of apoptosis-associated genes known to induce programed cell death through mRNA expressions of two matrix metalloproteinases (MMPs) that are involved in the degradation of collagen and basal membrane in luteal cells cultured in the treatment media. Our results show that the activity of MMP-2 gelatinase was higher in the CL2 and CL1 of luteal phase, was gradually decreased in the CH2 and CH3 of luteal phase. In particular, the expressions of P4-r and survival-associated genes (IGFr, PI3K, AKT, and mTOR) were strongly induced during CL3 stage, whereas the levels of these genes in corpus luteum (CL) were lower during CL2 and CL1 stages. In the cultured lutein cells analyzed, we found that as MMPs increase, genes related to apoptosis (20α-hydroxy steroid dehydrogenase and caspase-3) also increase. In other words, the results for P4-r and survival-related gene expression patterns in the luteal cells were contrary to the MMPs activation results. These results indicate that active MMPs are differentially expressed to induce the expression of genes associated with programed cell death from the degrading luteal cells. Therefore, our results suggest that the MMPs activation may lead to luteal cell development or death

Image-Object-Specific Prompt Learning for Few-Shot Class-Incremental Learning

While many FSCIL studies have been undertaken, achieving satisfactory performance, especially during incremental sessions, has remained challenging. One prominent challenge is that the encoder, trained with an ample base session training set, often underperforms in incremental sessions. In this study, we introduce a novel training framework for FSCIL, capitalizing on the generalizability of the Contrastive Language-Image Pre-training (CLIP) model to unseen classes. We achieve this by formulating image-object-specific (IOS) classifiers for the input images. Here, an IOS classifier refers to one that targets specific attributes (like wings or wheels) of class objects rather than the image's background. To create these IOS classifiers, we encode a bias prompt into the classifiers using our specially designed module, which harnesses key-prompt pairs to pinpoint the IOS features of classes in each session. From an FSCIL standpoint, our framework is structured to retain previous knowledge and swiftly adapt to new sessions without forgetting or overfitting. This considers the updatability of modules in each session and some tricks empirically found for fast convergence. Our approach consistently demonstrates superior performance compared to state-of-the-art methods across the miniImageNet, CIFAR100, and CUB200 datasets. Further, we provide additional experiments to validate our learned model's ability to achieve IOS classifiers. We also conduct ablation studies to analyze the impact of each module within the architecture.Comment: 8 pages, 4 figures, 4 table

Sofosbuvir-based therapy for patients with chronic hepatitis C: Early experience of its efficacy and safety in Korea

Background/AimsThe previous standard treatment for chronic hepatitis C (CHC) patients, comprising a combination of pegylated interferon (IFN) and ribavirin, was associated with suboptimal efficacy and severe adverse reactions. A new era of direct-acting antivirals is now dawning in Korea. Early experience of applying sofosbuvir-based therapy to CHC patients in Korea is reported herein.MethodsData on efficacy and safety were collected for CHC patients treated with a combination of sofosbuvir plus ribavirin or sofosbuvir/ledipasvir with or without ribavirin.ResultsThis retrospective study included 25 consecutive patients who received sofosbuvir-based therapy (19 with genotype 1b and 6 with genotype 2) at Seoul National University Hospital from May 2014 to April 2015. A virologic response was achieved at week 4 by 85.7% and 80% of the patients with genotypes 1b and 2, respectively. The HCV-RNA level decreased more slowly in IFN-experienced than in treatment-naïve patients with genotype 1b. However, the sustained virologic response at week 12 (SVR12) rate did not differ among these patients, and was as high as 100%. The presence of cirrhosis significantly increased the risk of a virologic response failure at week 4 (OR, 11.0; P=0.011) among patients with HCV genotype 1b. Only five patients (20%) experienced minor adverse events, including grade 1 fatigue and headache. The hemoglobin level decreased slightly after sofosbuvir-based therapy, but there was no case of premature discontinuation of this therapy.ConclusionsIn a real clinical practice, sofosbuvir-based therapy for CHC patients in Korea achieved optimal antiviral efficacy with insignificant adverse events. Long-term follow-up data are warranted to ensure the sustained antiviral efficacy and long-term safety of sofosbuvir-based IFN-free therapy

Tenofovir-associated nephrotoxicity in patients with chronic hepatitis B: two cases

Tenofovir disoproxil fumarate (TDF) is effective against chronic hepatitis B (CHB) infection and its use is increasing rapidly worldwide. However, it has been established that TDF is associated with renal toxicity in human immunodeficiency virus-infected patients, while severe or symptomatic TDF-associated nephrotoxicity has rarely been reported in patients with CHB. Here we present two patients with TDF-associated nephrotoxicity who were being treated for CHB infection. The first patient was found to have clinical manifestations of proximal renal tubular dysfunction and histopathologic evidence of acute tubular necrosis at 5 months after starting TDF treatment. The second patient developed acute kidney injury at 17 days after commencing TDF, and he was found to have membranoproliferative glomerulonephritis with acute tubular injury. The renal function improved in both patients after discontinuing TDF. We discuss the risk factors for TDF-associated renal toxicity and present recommendations for monitoring renal function during TDF therapy