High-Speed Colloidal Quantum Dot Photodiodes via Accelerating Charge Separation at Metal-Oxide Interface.

With ever-growing technological demands in the imaging sensor industry for autonomous driving and augmented reality, developing sensors that can satisfy not only image resolution but also the response speed becomes more challenging. Herein, the focus is on developing a high-speed photosensor capable of obtaining high-resolution, high-speed imaging with colloidal quantum dots (QDs) as the photosensitive material. In detail, high-speed QD photodiodes are demonstrated with rising and falling times of τr = 28.8 ± 8.34 ns and τf = 40 ± 9.81 ns, respectively, realized by fast separation of electron-hole pairs due to the action of internal electric field at the QD interface, mainly by the interaction between metal oxide and the QD's ligands. Such energy transfer relations are analyzed and interpreted with time-resolved photoluminescence measurements, providing physical understanding of the device and working principles.

Quantum cascade lasers with Y2O3 insulation layer operating at 8.1 µm.

SiO2 is a commonly used insulation layer for QCLs but has high absorption peak around 8 to 10 µm. Instead of SiO2, we used Y2O3 as an insulation layer for DC-QCL and successfully demonstrated lasing operation at the wavelength around 8.1 µm. We also showed 2D numerical analysis on the absorption coefficient of our DC-QCL structure with various parameters such as insulating materials, waveguide width, and mesa angle.

Alternative Patterning Process for Realization of Large-Area, Full-Color, Active Quantum Dot Display.

Although various colloidal quantum dot (QD) coating and patterning techniques have been developed to meet the demands in optoelectronic applications over the past years, each of the previously demonstrated methods has one or more limitations and trade-offs in forming multicolor, high-resolution, or large-area patterns of QDs. In this study, we present an alternative QD patterning technique using conventional photolithography combined with charge-assisted layer-by-layer (LbL) assembly to solve the trade-offs of the traditional patterning processes. From our demonstrations, we show repeatable QD patterning process that allows multicolor QD patterns in both large-area and microscale. Also, we show that the QD patterns are robust against additional photolithography processes and that the thickness of the QD patterns can be controlled at each position. To validate that this process can be applied to actual device applications as an active material, we have fabricated inverted, differently colored, active QD light-emitting device (QD-LED) on a pixelated substrate, which achieved maximum electroluminescence intensity of 23 770 cd/m2, and discussed the results. From our findings, we believe that our process provides a solution to achieving both high-resolution and large-scale QD pattern applicable to not only display, but also to practical photonic device research and development.

Circulating-tumor DNA Assessment in Diffuse Large B-cell Lymphoma to Determine Up-front Stem Cell Transplantation: A Pilot Study.

BACKGROUND/AIM: This study evaluated the possibility of clinical use of circulating-tumor DNA (ctDNA) as a biomarker to determine up-front autologous stem cell transplantation (auto-SCT) for patients with high-risk diffuse large B-cell lymphoma (DLBCL) in practice. PATIENTS AND METHODS: To explore the dynamics of ctDNA in DLBCL, blood samples were collected sequentially before and after treatment from patients with newly diagnosed DLBCL who received rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) chemotherapy. To conduct ctDNA genotyping and ctDNA monitoring simultaneously, targeted sequencing by cancer personalized profiling using deep sequencing was used. RESULTS: Ten patients between the ages of 50 and 60 years were enrolled. Based on the international prognostic index (IPI), seven patients were classified as high-IPI-risk group, and three patients were classified as low-IPI-risk group. The IPI risk group correlated with total metabolic tumor volume. All patients completed six cycles of R-CHOP chemotherapy, and seven patients achieved complete response. Changes in ctDNA mutation numbers did not correlate with changes in PET scan images and treatment response. In most high-risk patients, new mutations appeared in ctDNA after completion of chemotherapy that conceivably marked resistant clones. Notably, disease relapse did not occur in high-risk patients with poor prognostic mutations who underwent autologous SCT. CONCLUSION: ctDNA monitoring was meaningful in high-risk patients. Moreover, ctDNA and well-known prognostic factors should be considered in the decision making for auto-SCT. If a new genetic mutation in ctDNA with a negative prognosis would emerge during treatment, high-risk patients should consider auto-SCT.

Reliability of Alkaline Phosphatase for Differentiating Flare Phenomenon from Disease Progression with Bone Scintigraphy.

The flare phenomenon (FP) on bone scintigraphy after the initiation of systemic treatment seriously complicates evaluations of therapeutic response in patients with bone metastases. The aim of this study was to evaluate whether serum alkaline phosphatase (ALP) can differentiate FP from disease progression on bone scintigraphy in these patients. Breast or prostate cancer patients with bone metastases who newly underwent systemic therapy were reviewed. Pretreatment baseline and follow-up data, including age, pathologic factors, type of systemic therapy, radiologic and bone scintigraphy findings, and ALP levels, were obtained. Univariate and multivariate analyses of these factors were performed to predict FP. An increased extent and/or new lesions were found in 160 patients on follow-up bone scintigraphy after therapy. Among the 160 patients, 80 (50%) had an improvement on subsequent bone scintigraphy (BS), while subsequent scintigraphy also showed an increased uptake in 80 (50%, progression). Multiple regression analysis revealed that stable or decreased ALP was an independent predictor for FP (p < 0.0001). ALP was an independent predictor for FP on subgroup analysis for breast and prostate cancer (p = 0.001 and p = 0.0223, respectively). Results of the study suggest that ALP is a useful serologic marker to differentiate FP from disease progression on bone scintigraphy in patients with bone metastasis. Clinical interpretation for scintigraphic aggravation can be further improved by the ALP data and it may prevent fruitless changes of therapeutic modality by misdiagnosis of disease progression in cases of FP.

Impact of medication discontinuation on increased intestinal FDG accumulation in diabetic patients treated with metformin.

OBJECTIVE: We evaluated the impact of stopping medication for 2 days on reductions in the high intestinal FDG uptake induced by metformin. SUBJECTS AND METHODS: One hundred thirty-eight diabetic patients were divided into two groups: one in which the antihyperglycemic drug regimen included metformin (group A; n = 107) and one in which the regimen did not include metformin (group B; n = 31). Fifty-two patients without diabetes mellitus served as the control group (group C). Group A was divided into two subgroups: 77 patients (group A1) were taking metformin at the time of FDG PET/CT scans, whereas the remaining 30 patients (group A2) were asked to stop taking metformin for 2 days before PET/CT scans. In addition, 10 diabetic patients underwent two consecutive PET/CT scans before and after the discontinuation of metformin. The intestinal FDG uptake and blood glucose levels were compared among the four groups, as well as before and after the discontinuation of metformin. RESULTS: The high intestinal FDG uptake in group A1 was significantly reduced after the discontinuation of metformin (p < 0.001 vs group A2); thus, there were no significant differences among group A2, group B, and group C (p = 0.581-0.872). There were also no statistically significant differences in the blood glucose levels among the three groups of diabetic patients (p > 0.9). In 10 patients who underwent serial PET/CT scans, mean intestinal FDG uptake decreased by 64% without significant changes in the blood glucose level. Hidden colorectal malignancies were revealed in two patients after the discontinuation of medication. CONCLUSION: The discontinuation of metformin for 2 days is feasible for reducing the high intestinal FDG uptake induced by metformin.

Highly transparent phototransistor based on quantum-dots and ZnO bilayers for optical logic gate operation in visible-light.

Highly transparent optical logic circuits operated with visible light signals are fabricated using phototransistors with a heterostructure comprised of an oxide semiconductor (ZnO) with a wide bandgap and quantum dots (CdSe/ZnS QDs) with a small bandgap. ZnO serves as a highly transparent active channel, while the QDs absorb visible light and generate photoexcited charge carriers. The induced charge carriers can then be injected into the ZnO conduction band from the QD conduction band, which enables current to flow to activate the phototransistor. The photoexcited charge transfer mechanism is investigated using time-resolved photoluminescence spectroscopy, scanning Kelvin probe microscopy, and ultraviolet photoelectron spectroscopy. Measurements show that carriers in the QD conduction band can transfer to the ZnO conduction band under visible light illumination due to a change in the Fermi energy level. Moreover, the barrier for electron injection into the ZnO conduction band from the QD conduction band is low enough to allow photocurrent generation in the QDs/ZnO phototransistor. Highly transparent NOT, NOR, and NAND optical logic circuits are fabricated using the QDs/ZnO heterostructure and transparent indium tin oxide electrodes. This work provides a means of developing highly transparent optical logic circuits that can operate under illumination with low-energy photons such as those found in visible light.

Quantitative Assessment of Interim PET/CT Could Have More Prognostic Relevance than Visual Assessment for Predicting Clinical Outcome of Extranodal Diffuse Large B Cell Lymphoma.

BACKGROUND/AIM: The present study retrospectively investigated the predictive accuracy of interim positron emission tomography/computed tomography (iPET/CT) based on the Deauville 5-point scale (5-PS) and a quantitative SUV-based assessment in patients with extranodal (EN) diffuse large B cell lymphoma (DLBCL). PATIENTS AND METHODS: The Deauville 5-PS and the SUVmax reduction (ΔSUVmax) assessment for interpreting the response to iPET/CT were used. RESULTS: A total of 163 patients were enrolled in this study. With a median follow-up of 52.5 months, ΔSUVmax successfully predicted the survival outcomes of patients with one extranodal (EN) involvement in terms of overall survival (OS) (p=0.012) and progression-free survival (PFS) (p<0.001). Visual assessment using the Deauville 5-PS did not predict survival outcomes in patients with one or more EN involvements in terms of OS and PFS. CONCLUSION: The quantitative SUV-based assessment with iPET/CT was a significant prognosticator for long-term survival outcomes, especially in patients with one EN involvement.

Corrigendum to "Visualization of the Biological Behavior of Tumor-Associated Macrophages in Living Mice with Colon Cancer Using Multimodal Optical Reporter Gene Imaging" [Neoplasia 18 (2016) 133-141].

[This corrects the article DOI: 10.1016/j.neo.2016.01.004.].

Incidental focal F-18 FDG accumulation in lung parenchyma without abnormal CT findings.

F-18 fluorodeoxyglucose (FDG) PET/CT that simultaneously offers anatomic and metabolic information is widely used and has become an effective modality in many clinical fields, especially oncology. For accurate interpretation, it is necessary to understand false-positive findings in the F-18 FDG PET image, such as physiologic conditions, findings related to patients' medical and surgical histories, normal variants, and artificial conditions. We report three cases of incidental focal F-18 FDG accumulation in lung parenchyma without abnormal CT findings in the PET/CT images. In the primary PET/CT studies, two cases showed single and one case showed multiple FDG foci in the lung without any CT abnormalities. All FDG accumulations disappeared in PET/CT studies repeated 1-3 days after the primary scannings. These artifacts are probably related to microembolisms attributable to the intravenous injection of F-18 FDG. Therefore, a cautious interpretation of the correspondence between anatomic and metabolic images is required and repeated PET/CT is helpful.