The Impact of Partial Carrier Confinement on Stimulated Emission in Strongly Confined Perovskite Nanocrystals.

Semiconductor lead halide perovskites are excellent candidates for realizing low threshold light amplification due to their tunable and highly efficient luminescence, ease of processing, and strong light-matter interactions. However, most studies on optical gain have addressed bulk films, nanowires, or nanocrystals that exhibit little or no size quantization. Here, we show by means of a multitude of optical spectroscopy methods that small CsPbBr3 nanocrystals (NCs) exhibit a progressive red shift of the band-edge transition upon addition of electron-hole pairs, at least one carrier of which occupies a 2-fold degenerate, delocalized state in agreement with strong confinement. We demonstrate that this combination results in a threshold for biexciton gain, well below the limit of one electron-hole pair on average per NC. On the other hand, both the luminescent lifetime and the optical Stark effect of 4.7 nm CsPbBr3 NCs indicate that the oscillator strength of the band-edge transition is considerably smaller than expected from the band-edge absorption. We assign this discrepancy to a mixed confinement regime, with one delocalized and one localized charge carrier, and show that the concomitant reduction of the oscillator strength for stimulated emission accounts for the surprisingly small material gain observed in small NCs. The conclusion of mixed confinement aligns with studies reporting small and large polarons for holes and electrons in lead halide perovskite nanocrystals, respectively, and creates opportunities for understanding multiexciton photophysics in confined perovskite materials.

ON/OFF based synergetic plasmonic photothermal drug release approach through core-satellite like mussel-inspired polydopamine nanoparticles.

One of the studies on new drug delivery and release systems that has increased in recent years is the study using plasmonic nanoparticles. In this study, polydopamine nanoparticles (PDOP NPs), which contribute to photothermal drug release by near infrared radiation (NIR), were decorated with gold nanoparticles (AuNPs) to utilize their plasmonic properties, and a core-satellite-like system was formed. With this approach, epirubicin (EPI)-loaded PDOP NPs were prepared by utilizing the plasmonic properties of AuNPs. Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Diffraction (XRD) methods were used to evaluate the structural properties of these particles. The release behavior of the prepared structures in acidic (pH 5.0) and neutral (pH 7.4) environments based on the ON/OFF approach was also examined. The biocompatibility properties of the particles were evaluated on mouse fibroblast (L929) and anticancer activities on neuroblastoma (SH-SY5Y) cells. The effects of prepared EPI-loaded particles and laser-controlled drug release on ROS production, genotoxicity, and apoptosis were also investigated in SH-SY5Y cells. With the calculated combination index (CI) value, it was shown that the activity of EPI-loaded AuNP@PDOP NPs increased synergistically with the ON/OFF-based approach. The developed combination approach is considered to be remarkable and promising for further evaluation before clinical use.

Biomonitoring of Oxidative-Stress-Related Genotoxic Damage in Patients with End-Stage Renal Disease.

Chronic kidney disease (CKD), a common progressive renal failure characterized by the permanent loss of functional nephrons can rapidly progress to end-stage renal disease, which is known to be an irreversible renal failure. In the therapy of ESRD, there are controversial suggestions about the use of regular dialysis, since it is claimed to increase oxidative stress, which may increase mortality in patients. In ESRD, oxidative-stress-related DNA damage is expected to occur, along with increased inflammation. Many factors, including heavy metals, have been suggested to exacerbate the damage in kidneys; therefore, it is important to reveal the relationship between these factors in ESRD patients. There are very few studies showing the role of oxidative-stress-related genotoxic events in the progression of ESRD patients. Within the scope of this study, genotoxic damage was evaluated using the comet assay and 8-OHdG measurement in patients with ESRD who were undergoing hemodialysis. The biochemical changes, the levels of heavy metals (aluminum, arsenic, cadmium, lead, and mercury) in the blood, and the oxidative biomarkers, including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and malondialdehyde (MDA) levels were evaluated, and their relationship with genotoxic damages was revealed. Genotoxicity, oxidative stress, and heavy-metal levels, except mercury, increased significantly in all renal patients. DNA damage, 8OHdG, and MDA significantly increased, and GSH significantly decreased in patients undergoing dialysis, compared with those not having dialysis. The duration and the severity of disease was positively correlated with increased aluminum levels and moderate positively correlated with increased DNA damage and cadmium levels. In conclusion, this study revealed that the oxidative-stress-related DNA damage, and also the levels of Al and Cd, increased in ESRD patients. It is assumed that these changes may play an important role in the progression of renal damage. Approaches for reducing oxidative-stress-related DNA damage and heavy-metal load in ESRD patients are recommended.

Highly-Directional, Highly-Efficient Solution-Processed Light-Emitting Diodes of All-Face-Down Oriented Colloidal Quantum Well Self-Assembly.

Semiconductor colloidal quantum wells (CQWs) provide anisotropic emission behavior originating from their anisotropic optical transition dipole moments (TDMs). Here, solution-processed colloidal quantum well light-emitting diodes (CQW-LEDs) of a single all-face-down oriented self-assembled monolayer (SAM) film of CQWs that collectively enable a supreme level of IP TDMs at 92% in the ensemble emission are shown. This significantly enhances the outcoupling efficiency from 22% (of standard randomly-oriented emitters) to 34% (of face-down oriented emitters) in the LED. As a result, the external quantum efficiency reaches a record high level of 18.1% for the solution-processed type of CQW-LEDs, putting their efficiency performance on par with the hybrid organic-inorganic evaporation-based CQW-LEDs and all other best solution-processed LEDs. This SAM-CQW-LED architecture allows for a high maximum brightness of 19,800 cd m-2 with a long operational lifetime of 247 h at 100 cd m-2 as well as a stable saturated deep-red emission (651 nm) with a low turn-on voltage of 1.7 eV at a current density of 1 mA cm-2 and a high J90 of 99.58 mA cm-2 . These findings indicate the effectiveness of oriented self-assembly of CQWs as an electrically-driven emissive layer in improving outcoupling and external quantum efficiencies in the CQW-LEDs.

In vitro toxicity of naringin and berberine alone, and encapsulated within PMMA nanoparticles.

Phytochemical compounds, such as naringin and berberine, have been used for many years due to their antioxidant activities, and consequently, beneficial health effects. In this study, it was aimed to evaluate the antioxidant properties of naringin, berberine and poly(methylmethacrylate) (PMMA) nanoparticles (NPs) encapsulated with naringin or berberine and their possible cytotoxic, genotoxic, and apoptotic effects on mouse fibroblast (NIH/3 T3) and colon cancer (Caco-2) cells. According to the results of the study, it was found that the 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition antioxidant activity of naringin, berberine, and naringin or berberine encapsulated PMMA NPs, was significantly increased at higher tested concentrations due to the antioxidant effects of naringin, berberine and naringin or berberine encapsulated PMMA NPs. As a result of the cytotoxicity assay, after 24-, 48- and 72-h of exposure, all of the studied compounds caused cytotoxic effects in both cell lines. Genotoxic effects of studied compounds were not registered at lower tested concentrations. Based on these data, polymeric nanoparticles encapsulated with naringin or berberine may contribute to new treatment approaches for cancer, but further in vivo and in vitro research is required.

Quantum Dot Patterning and Encapsulation by Maskless Lithography for Display Technologies.

For their unique optical properties, quantum dots (QDs) have been extensively used as light emitters in a number of photonic and optoelectronic applications. They even met commercialization success through their implementation in high-end displays with unmatched brightness and color rendering. For such applications, however, QDs must be shielded from oxygen and water vapor, which are known to degrade their optical properties over time. Even with highly qualitative QDs, this can only be achieved through their encapsulation between barrier layers. With the emergence of mini- and microLED for higher contrast and miniaturized displays, new strategies must be found for the concomitant patterning and encapsulation of QDs, with sub-millimeter resolution. To this end, we developed a new approach for the direct patterning of QDs through maskless lithography. By combining QDs in photopolymerizable resins with digital light processing (DLP) projectors, we developed a versatile and massively parallel fabrication process for the additive manufacturing of functional structures that we refer to as QD pockets. These 3D heterostructures are designed to provide isotropic encapsulation of the QDs, and hence prevent edge ingress from the lateral sides of QD films, which remains a shortcoming of the current technologies.

Is a non-cytotoxic and non-genotoxic novel bioinspired dipeptide structure synthesis possible for theragnostic applications?

The diagnosis and treatment of the diseases in a certain coordination is a subject that has been emphasized in recent years. Theragnostics approaches allow simultaneous diagnosis and treatment of chronic diseases such as cancer. An ideal theragnostic should be biocompatible and can be used safely in humans. Although several types of theragnostics have been developed, none of yet satisfied these criteria. Bioinspired materials with noble metal centers encapsulating therapeutic and imaging agents were shown to possess theragnostic activities. In this study, it was aimed to synthesize, characterize, and evaluate the cytotoxic and genotoxic effects of self-assembly of diphenylalanine (Phe-Phe) dipeptides presence of mercury (Hg2+) ions to be used for theragnostic. Cytotoxicity and genotoxicity studies were done in mouse fibroblast (NIH/3T3) cells by 3-(4,5-Dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide (MTT) and single cell gel electrophoresis (Comet) assays, respectively. It was found that cell viability decreased in a dose-dependent manner in 24-, 48-, and 72-h treatment. Also, Phe-Phe dipeptides did not cause any significant changes in DNA damage at the concentrations of 1, 2, and 5 mg/mL in 4- and 24-h exposures. In the 48-h exposure, Phe-Phe peptide exposure at concentrations of 2 and 5 mg/mL caused a significant increase in DNA damage and in the 72-h of exposure, a significant increase in DNA damage was observed at all studied concentrations. According to the results of the study, it can be said that Phe-Phe dipeptides presence of Hg2+ ions are biocompatible and can be used safely for theragnostic purposes.

Observation of optical gain from aqueous quantum well heterostructures in water.

Although achieving optical gain using aqueous solutions of colloidal nanocrystals as a gain medium is exceptionally beneficial for bio-optoelectronic applications, the realization of optical gain in an aqueous medium using solution-processed nanocrystals has been extremely challenging because of the need for surface modification to make nanocrystals water dispersible while still maintaining their gain. Here, we present the achievement of optical gain in an aqueous medium using an advanced architecture of CdSe/CdS@CdxZn1-xS core/crown@gradient-alloyed shell colloidal quantum wells (CQWs) with an ultralow threshold of ∼3.4 µJ cm-2 and an ultralong gain lifetime of ∼2.6 ns. This demonstration of optical gain in an aqueous medium is a result of the carefully heterostructured CQWs having large absorption cross-section and gain cross-section in addition to inherently slow Auger recombination in these CQWs. Furthermore, we show low-threshold in-water amplified spontaneous emission (ASE) from these aqueous CQWs with a threshold of 120 µJ cm-2. In addition, we demonstrate a whispering gallery mode laser with a low threshold of ∼30 µJ cm-2 obtained by incorporating films of CQWs by exploiting layer-by-layer approach on a fiber. The observation of low-threshold optical gain with ultralong gain lifetime presents a significant step toward the realization of advanced optofluidic colloidal lasers and their continuous-wave pumping.

PATIENT AND STAFF DOSES FOR VARIOUS INTERVENTIONAL RADIOLOGY AND CARDIOLOGY EXAMINATIONS IN TURKEY.

This study aims to determine the radiation doses of patients and staff during different interventional radiology and cardiology examinations. Dose measurements for interventional radiology examinations were performed in Ibn-i Sina Hospital of Ankara University using Siemens Artis-Zee medical imaging system. Patient dose measurement was carried out for interventional cardiology examinations in Cardiology Department of TOBB-ETU University, Medical Faculty Hospital using Philips Allura Centron interventional X-ray system. Patient doses were obtained in terms of kerma area product (KAP) and cumulative air kerma (CAK) from KAP meter attached to the angiography system. Performance tests of the angiography system were performed before patient dose measurements. Staff dose measurements were carried out with thermoluminescence dosimeters (TLD-100) placed in certain areas on the staff. Patient dose measurements were performed for 15 different interventional radiology examinations on a total of 431 patients and for four different cardiology examinations on a total of 299 patients. Monte Carlo based PCXMC 2.0 program was used to calculate patient effective doses. Lower extremity arteriography was the most common examination with a mean KAP value of 30 Gy cm2 and mean effective dose value of 1.2 mSv for total number of 194 patients. Mean KAP values calculated for coronary angiography, percutaneous coronary intervention, electrophysiological procedures and radiofrequency cardiac ablation examinations were 62.8, 162.8, 16.7 and 70.6 Gy cm2, respectively. Radiologist, nurse and technician effective dose normalised to the unit KAP of patient dose were 0.15, 0.11 and 0.14 µSv Gy-1 cm-2. Similarly, cardiologist, nurse and technician effective dose normalised to the unit KAP of patient dose were 0.22, 0.15 and 0.09 µSv Gy-1 cm-2. Measured KAP and CAK values vary depending on the type and complexity of the examination. The measured staff doses during cardiac examinations were higher when compared with that measured for interventional radiology as expected.

Evaluation of bacterial uptake, antibacterial efficacy against Escherichia coli, and cytotoxic effects of moxifloxacin-loaded solid lipid nanoparticles.

Moxifloxacin (MOX) is an important antibiotic commonly used in the treatment of recurrent Escherichia coli (E. coli) infections. The aim of this study was to investigate its antibacterial efficiency when used with solid lipid nanoparticles (SNLs) and nanostructured lipid carriers (NLCs) as delivery vehicles. For this purpose we designed two SLNs (SLN1 and SLN2) and two NLCs (NLC1 and NLC2) of different characteristics (particle size, size distribution, zeta potential, and encapsulation efficiency) and loaded them with MOX to determine its release, antibacterial activity against E. coli, and their cytotoxicity to the RAW 264.7 monocyte/macrophage-like cell line in vitro. With bacterial uptake of 57.29 %, SLN1 turned out to be significantly more effective than MOX given as standard solution, whereas SLN2, NLC1, and NLC2 formulations with respective bacterial uptakes of 50.74 %, 39.26 %, and 32.79 %, showed similar activity to standard MOX. Cytotoxicity testing did not reveal significant toxicity of nanoparticles, whether MOX-free or MOX-loaded, against RAW 264.7 cells. Our findings may show the way for a development of effective lipid carriers that reduce side effects and increase antibacterial treatment efficacy in view of the growing antibiotic resistance.

Efficacy of preheated chelating agents on calcium ion removal from instrumented root canals.

BACKGROUND: The heating of chelating agents such as EDTA increases dentin wettability by decreasing surface tension. However, the calcium ion release effect of preheated chelating agents in instrumented root canals has not yet been mentioned. In this study, it was aimed to evaluate the number of calcium ions removed by the pre-heated chelating agents from the root canals. MATERIAL AND METHODS: After 51 bovine teeth were instrumented, three of them were separated as negative controls and the remaining teeth were divided into six groups according to the temperature of the solution (at 22 or 37ºC): EDTA-22, CITRIC-22, QMix-22, EDTA-37, CITRIC-37 and QMix-37. Following irrigation, calcium ion levels were determined by atomic absorption spectrophotometer in chelating agents collected from the root canals. RESULTS: QMix solution eliminated significantly more calcium ions than other chelating agents at different temperatures (p< 0.05). Regardless of the heating, QMix and 17% EDTA were significantly superior to 40% Citric acid (p< 0.05) while no significant difference was detected between QMix and 17% EDTA groups (p< 0.05). Heating all chelating agents did not significantly increase their ability to remove calcium ions from pre-instrumented root canals (P< 0.05). In the SEM examination, it was observed that the smear layer was removed from the middle third of the roots, except for the negative control group. CONCLUSIONS: Temperature changes have shown that these agents do not increase the ability of the smear layer to dissolve the inorganic structure. QMix at different temperatures may be recommended to use as the final chelating agent. Key words:EDTA, citric acid, QMix, calcium ions, temperature.

Cyan Emission in Two-Dimensional Colloidal Cs2CdCl4:Sb3+ Ruddlesden-Popper Phase Nanoplatelets.

Metal halide perovskites are one of the most investigated materials in optoelectronics, with their lead-based counterparts being renowned for their enhanced optoelectronic performance. The 3D CsPbX3 structure has set the standard with many studies currently attempting to substitute lead with other metals while retaining the properties of this material. This effort has led to the fabrication of metal halides with lower dimensionality, wherein particular 2D layered perovskite structures have captured attention as inspiration for the next generation of colloidal semiconductors. Here we report the synthesis of the Ruddlesden-Popper Cs2CdCl4:Sb3+ phase as colloidal nanoplatelets (NPs) using a facile hot injection approach under atmospheric conditions. Through strict adjustment of the synthesis parameters with emphasis on the ligand ratio, we obtained NPs with a relatively uniform size and good morphological control. The particles were characterized through transmission electron microscopy, synchrotron X-ray diffraction, and pair distribution function analysis. The spectroscopic characterization revealed most strikingly an intense cyan emission under UV excitation with a measured PLQY of ∼20%. The emission was attributed to the Sb3+-doping within the structure.

Near-Field Energy Transfer into Silicon Inversely Proportional to Distance Using Quasi-2D Colloidal Quantum Well Donors.

Silicon is the most prevalent material system for light-harvesting applications; however, its inherent indirect bandgap and consequent weak absorption limits its potential in optoelectronics. This paper proposes to address this limitation by combining the sensitization of silicon with extraordinarily large absorption cross sections of quasi-2D colloidal quantum well nanoplatelets (NPLs) and to demonstrate excitation transfer from these NPLs to bulk silicon. Here, the distance dependency, d, of the resulting Förster resonant energy transfer from the NPL monolayer into a silicon substrate is systematically studied by tuning the thickness of a spacer layer (of Al2 O3 ) in between them (varied from 1 to 50 nm in thickness). A slowly varying distance dependence of d-1 with 25% efficiency at a donor-acceptor distance of 20 nm is observed. These results are corroborated with full electromagnetic solutions, which show that the inverse distance relationship emanates from the delocalized electric field intensity across both the NPL layer and the silicon because of the excitation of strong in-plane dipoles in the NPL monolayer. These findings pave the way for using colloidal NPLs as strong light-harvesting donors in combination with crystalline silicon as an acceptor medium for application in photovoltaic devices and other optoelectronic platforms.

Evaluation of cytotoxic and genotoxic effects of paclitaxel-loaded PLGA nanoparticles in neuroblastoma cells.

Neuroblastoma, a neoplasm of the sympathetic nervous system, is the second most common extracranial malignant tumor of childhood and the most common solid tumor of infancy. Paclitaxel (taxol), a diterpenoid pseudoalkaloid isolated from the shells of Taxus brevifolia, is the first taxane derivative used in the clinic for cancer treatment. Poly (lactic-co-glycolic acid) (PLGA) is one of the most successfully used biodegradable polymers for drug delivery which has a minimum systemic toxicity. This study aimed to evaluate the cytotoxicity and genotoxicity of paclitaxel nanoencapsulated with PLGA. Cytotoxic effects were determined by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method and genotoxic effects were determined by single cell gel electrophoresis (Comet) method in human neuroblastoma cells (SH-SY5Y). According to our results, the viability of cells treated with concentrations higher than 10 nM of free paclitaxel and paclitaxel loaded PLGA nanoparticles for 48 and 72 h was found lower than 50%. Additionally, DNA damage increased with the increase of nanoparticle dose when the cells exposed to paclitaxel loaded PLGA nanoparticles for 24, 48 and 72 h. It can be concluded that PLGA nanoparticles can be considered as a biocompatible carrier system for drug delivery and might be promising agent against neuroblastoma.

Self-Resonant Microlasers of Colloidal Quantum Wells Constructed by Direct Deep Patterning.

Here, the first account of self-resonant fully colloidal µ-lasers made from colloidal quantum well (CQW) solution is reported. A deep patterning technique is developed to fabricate well-defined high aspect-ratio on-chip CQW resonators made of grating waveguides and in-plane reflectors. The fabricated waveguide-coupled laser, enabling tight optical confinement, assures in-plane lasing. CQWs of the patterned layers are closed-packed with sharp edges and residual-free lifted-off surfaces. Additionally, the method is successfully applied to various nanoparticles including colloidal quantum dots and metal nanoparticles. It is observed that the patterning process does not affect the nanocrystals (NCs) immobilized in the attained patterns and the different physical and chemical properties of the NCs remain pristine. Thanks to the deep patterning capability of the proposed method, patterns of NCs with subwavelength lateral feature sizes and micron-scale heights can possibly be fabricated in high aspect ratios.

Light-Induced Paramagnetism in Colloidal Ag+-Doped CdSe Nanoplatelets.

We describe a study of the magneto-optical properties of Ag+-doped CdSe colloidal nanoplatelets (NPLs) that were grown using a novel doping technique. In this work, we used magnetic circularly polarized luminescence and magnetic circular dichroism spectroscopy to study light-induced magnetism for the first time in 2D solution-processed structures doped with nominally nonmagnetic Ag+ impurities. The excitonic circular polarization (PX) and the exciton Zeeman splitting (ΔEZ) were recorded as a function of the magnetic field (B) and temperature (T). Both ΔEZ and PX have a Brillouin-function-like dependence on B and T, verifying the presence of paramagnetism in Ag+-doped CdSe NPLs. The observed light-induced magnetism is attributed to the transformation of nonmagnetic Ag+ ions into Ag2+, which have a nonzero magnetic moment. This work points to the possibility of incorporating these nanoplatelets into spintronic devices, in which light can be used to control the spin injection.

Ultrahigh Green and Red Optical Gain Cross Sections from Solutions of Colloidal Quantum Well Heterostructures.

We demonstrate amplified spontaneous emission (ASE) in solution with ultralow thresholds of 30 µJ/cm2 in red and of 44 µJ/cm2 in green from engineered colloidal quantum well (CQW) heterostructures. For this purpose, CdSe/CdS core/crown CQWs, designed to hit the green region, and CdSe/CdS@CdxZn1-xS core/crown@gradient-alloyed shell CQWs, further tuned to reach the red region by shell alloying, were employed to achieve high-performance ASE in the visible range. The net modal gain of these CQWs reaches 530 cm-1 for the green and 201 cm-1 for the red, 2-3 orders of magnitude larger than those of colloidal quantum dots (QDs) in solution. To explain the root cause for ultrahigh gain coefficient in solution, we show for the first time that the gain cross sections of these CQWs is ≥3.3 × 10-14 cm2 in the green and ≥1.3 × 10-14 cm2 in the red, which are two orders of magnitude larger compared to those of CQDs.

Optical Microfluidic Waveguides and Solution Lasers of Colloidal Semiconductor Quantum Wells.

The realization of high-quality lasers in microfluidic devices is crucial for numerous applications, including biological and chemical sensors and flow cytometry, and the development of advanced lab-on-chip (LOC) devices. Herein, an ultralow-threshold microfluidic single-mode laser is proposed and demonstrated using an on-chip cavity. CdSe/CdS@Cdx Zn1- x S core/crown@gradient-alloyed shell colloidal semiconductor quantum wells (CQWs) dispersed in toluene are employed in the cavity created inside a poly(dimethylsiloxane) (PDMS) microfluidic device using SiO2 -protected Ag mirrors to achieve in-solution lasing. Lasing from such a microfluidic device having CQWs solution as a microfluidic gain medium is shown for the first time with a record-low optical gain threshold of 17.1 µJ cm- ² and lasing threshold of 68.4 µJ cm- ² among all solution-based lasing demonstrations. In addition, air-stable SiO2 protected Ag films are used and designed to form highly tunable and reflective mirrors required to attain a high-quality Fabry-Pérot cavity. These realized record-low thresholds emanate from the high-quality on-chip cavity together with the core/crown@gradient-alloyed shell CQWs having giant gain cross-section and slow Auger rates. This microfabricated CQW laser provides a compact and inexpensive coherent light source for microfluidics and integrated optics covering the visible spectral region.

Plasma prolidase levels are high in schizophrenia but not in first-episode psychosis.

An increasing number of studies have focussed on the neurobiology of schizophrenia (SCH), contributing to a better understanding of this disorder. Prolidase is a metalloprotease found in various tissues, which has been associated with the concentrations of proline, a neurotransmitter, in the brain. There is evidence to suggest that elevated proline levels play a role in SCH. The aim of the present study was to compare plasma proline levels in patients with drug-naive first-episode psychosis (FEP) and in those with SCH. Patients diagnosed with FEP (n = 26) and SCH (n = 26) were recruited for this study, in addition to healthy control volunteers (n = 26). Plasma prolidase levels were found to be elevated in the SCH group compared to drug-naive FEP and healthy control groups. This finding indicates that prolidase levels are higher in SCH patients, while levels in patients with drug-naive FEP are similar to those of healthy control. Follow-up studies are needed to provide a better understanding of prolidase in the etiopathogenesis of SCH.

Optical Gain in Ultrathin Self-Assembled Bi-Layers of Colloidal Quantum Wells Enabled by the Mode Confinement in their High-Index Dielectric Waveguides.

This study demonstrates an ultra-thin colloidal gain medium consisting of bi-layers of colloidal quantum wells (CQWs) with a total film thickness of 14 nm integrated with high-index dielectrics. To achieve optical gain from such an ultra-thin nanocrystal film, hybrid waveguide structures partly composed of self-assembled layers of CQWs and partly high-index dielectric material are developed and shown: in asymmetric waveguide architecture employing one thin film of dielectric underneath CQWs and in the case of quasi-symmetric waveguide with a pair of dielectric films sandwiching CQWs. Numerical modeling indicates that the modal confinement factor of ultra-thin CQW films is enhanced in the presence of the adjacent dielectric layers significantly. The active slabs of these CQW monolayers in the proposed waveguide structure are constructed with great care to obtain near-unity surface coverage, which increases the density of active particles, and to reduce the surface roughness to sub-nm scale, which decreases the scattering losses. The excitation and propagation of amplified spontaneous emission (ASE) along these active waveguides are experimentally demonstrated and numerically analyzed. The findings of this work offer possibilities for the realization of ultra-thin electrically driven colloidal laser devices, providing critical advantages including single-mode lasing and high electrical conduction.