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Diffusion-based generative models have emerged as powerful tools in the realm of generative modeling. Despite extensive research on denoising across various timesteps and noise levels, a conflict persists regarding the relative difficulties of the denoising tasks. While various studies argue that lower timesteps present more challenging tasks, others contend that higher timesteps are more difficult. To address this conflict, our study undertakes a comprehensive examination of task difficulties, focusing on convergence behavior and changes in relative entropy between consecutive probability distributions across timesteps. Our observational study reveals that denoising at earlier timesteps poses challenges characterized by slower convergence and higher relative entropy, indicating increased task difficulty at these lower timesteps. Building on these observations, we introduce an easy-to-hard learning scheme, drawing from curriculum learning, to enhance the training process of diffusion models. By organizing timesteps or noise levels into clusters and training models with descending orders of difficulty, we facilitate an order-aware training regime, progressing from easier to harder denoising tasks, thereby deviating from the conventional approach of training diffusion models simultaneously across all timesteps. Our approach leads to improved performance and faster convergence by leveraging the benefits of curriculum learning, while maintaining orthogonality with existing improvements in diffusion training techniques. We validate these advantages through comprehensive experiments in image generation tasks, including unconditional, class-conditional, and text-to-image generation., Comment: 22 pages, 8 figures, 5 tables

Diffusion models have achieved remarkable success across a range of generative tasks. Recent efforts to enhance diffusion model architectures have reimagined them as a form of multi-task learning, where each task corresponds to a denoising task at a specific noise level. While these efforts have focused on parameter isolation and task routing, they fall short of capturing detailed inter-task relationships and risk losing semantic information, respectively. In response, we introduce Switch Diffusion Transformer (Switch-DiT), which establishes inter-task relationships between conflicting tasks without compromising semantic information. To achieve this, we employ a sparse mixture-of-experts within each transformer block to utilize semantic information and facilitate handling conflicts in tasks through parameter isolation. Additionally, we propose a diffusion prior loss, encouraging similar tasks to share their denoising paths while isolating conflicting ones. Through these, each transformer block contains a shared expert across all tasks, where the common and task-specific denoising paths enable the diffusion model to construct its beneficial way of synergizing denoising tasks. Extensive experiments validate the effectiveness of our approach in improving both image quality and convergence rate, and further analysis demonstrates that Switch-DiT constructs tailored denoising paths across various generation scenarios., Comment: Project Page: https://byeongjun-park.github.io/Switch-DiT

We present Diffusion Model Patching (DMP), a simple method to boost the performance of pre-trained diffusion models that have already reached convergence, with a negligible increase in parameters. DMP inserts a small, learnable set of prompts into the model's input space while keeping the original model frozen. The effectiveness of DMP is not merely due to the addition of parameters but stems from its dynamic gating mechanism, which selects and combines a subset of learnable prompts at every step of the generative process (e.g., reverse denoising steps). This strategy, which we term "mixture-of-prompts", enables the model to draw on the distinct expertise of each prompt, essentially "patching" the model's functionality at every step with minimal yet specialized parameters. Uniquely, DMP enhances the model by further training on the same dataset on which it was originally trained, even in a scenario where significant improvements are typically not expected due to model convergence. Experiments show that DMP significantly enhances the converged FID of DiT-L/2 on FFHQ 256x256 by 10.38%, achieved with only a 1.43% parameter increase and 50K additional training iterations., Comment: Project page: https://sangminwoo.github.io/DMP

This technical report introduces Pegasus-1, a multimodal language model specialized in video content understanding and interaction through natural language. Pegasus-1 is designed to address the unique challenges posed by video data, such as interpreting spatiotemporal information, to offer nuanced video content comprehension across various lengths. This technical report overviews Pegasus-1's architecture, training strategies, and its performance in benchmarks on video conversation, zero-shot video question answering, and video summarization. We also explore qualitative characteristics of Pegasus-1 , demonstrating its capabilities as well as its limitations, in order to provide readers a balanced view of its current state and its future direction.

Despite the recent exceptional rise in power conversion efficiency of perovskite solar cells (PSCs), surface defects and ion migration related instability are still present in PSCs. The chain length and binding energy of the passivation material play important roles in defect passivation, ion migration, moisture stability, and device-performance improvement. We synthesized three sulfonated ammonium compounds and investigated the ef-fect of post-passivation with these compounds on ion-migration and stability. New materials with high binding energy include octylamine (OA) functionalized with sulfanilic acid (OAS), p-toluenesulfonic acid (OAT), and camphorsulfonic acid (OAC). The passivation improves power conversion efficiency (PCE) from 21.06% for the control to 24.37% for the devices treated with OAC. The champion device's hysteresis index decreased to 0.01 compared to 0.11 for the control device, which is the lowest reported so far. Furthermore, the passivated perovskite films retain over 85% of their initial PCE under 60% relative humidity for 1,600 h, and the device with OAC maintains over 90% of its initial operational long-term device stability without encapsulation for 600 h under 1 sun-illumination.

In this paper, we address the performance degradation of efficient diffusion models by introducing Multi-architecturE Multi-Expert diffusion models (MEME). We identify the need for tailored operations at different time-steps in diffusion processes and leverage this insight to create compact yet high-performing models. MEME assigns distinct architectures to different time-step intervals, balancing convolution and self-attention operations based on observed frequency characteristics. We also introduce a soft interval assignment strategy for comprehensive training. Empirically, MEME operates 3.3 times faster than baselines while improving image generation quality (FID scores) by 0.62 (FFHQ) and 0.37 (CelebA). Though we validate the effectiveness of assigning more optimal architecture per time-step, where efficient models outperform the larger models, we argue that MEME opens a new design choice for diffusion models that can be easily applied in other scenarios, such as large multi-expert models., Comment: To be published in the AAAI 2024 Proceedings Main Track

Self-supervised contrastive learning (CL) has achieved state-of-the-art performance in representation learning by minimizing the distance between positive pairs while maximizing that of negative ones. Recently, it has been verified that the model learns better representation with diversely augmented positive pairs because they enable the model to be more view-invariant. However, only a few studies on CL have considered the difference between augmented views, and have not gone beyond the hand-crafted findings. In this paper, we first observe that the score-matching function can measure how much data has changed from the original through augmentation. With the observed property, every pair in CL can be weighted adaptively by the difference of score values, resulting in boosting the performance of the existing CL method. We show the generality of our method, referred to as ScoreCL, by consistently improving various CL methods, SimCLR, SimSiam, W-MSE, and VICReg, up to 3%p in k-NN evaluation on CIFAR-10, CIFAR-100, and ImageNet-100. Moreover, we have conducted exhaustive experiments and ablations, including results on diverse downstream tasks, comparison with possible baselines, and improvement when used with other proposed augmentation methods. We hope our exploration will inspire more research in exploiting the score matching for CL.

Traditional robotic mechanisms contain a series of rigid links connected by rotational joints that provide powered motion, all of which is controlled by a central processor. By contrast, analogous mechanisms found in nature, such as octopus tentacles, contain sensors, actuators, and even neurons distributed throughout the appendage, thereby allowing for motion with superior complexity, fluidity, and reaction time. Smart materials provide a means with which we can mimic these features artificially. These specialized materials undergo shape change in response to changes in their environment. Previous studies have developed material-based actuators that could produce targeted shape changes. Here we extend this capability by introducing a novel computational and experimental method for design and synthesis of material-based morphing mechanisms capable of achieving complex pre-programmed motion. By combining active and passive materials, the algorithm can encode the desired movement into the material distribution of the mechanism. We demonstrate this new capability by de novo design of a 3D printed self-tying knot. This method advances a new paradigm in mechanism design that could enable a new generation of material-driven machines that are lightweight, adaptable, robust to damage, and easily manufacturable by 3D printing.

Recent progress in single-image 3D generation highlights the importance of multi-view coherency, leveraging 3D priors from large-scale diffusion models pretrained on Internet-scale images. However, the aspect of novel-view diversity remains underexplored within the research landscape due to the ambiguity in converting a 2D image into 3D content, where numerous potential shapes can emerge. Here, we aim to address this research gap by simultaneously addressing both consistency and diversity. Yet, striking a balance between these two aspects poses a considerable challenge due to their inherent trade-offs. This work introduces HarmonyView, a simple yet effective diffusion sampling technique adept at decomposing two intricate aspects in single-image 3D generation: consistency and diversity. This approach paves the way for a more nuanced exploration of the two critical dimensions within the sampling process. Moreover, we propose a new evaluation metric based on CLIP image and text encoders to comprehensively assess the diversity of the generated views, which closely aligns with human evaluators' judgments. In experiments, HarmonyView achieves a harmonious balance, demonstrating a win-win scenario in both consistency and diversity., Comment: Project page: https://byeongjun-park.github.io/HarmonyView

Diffusion models generate highly realistic images by learning a multi-step denoising process, naturally embodying the principles of multi-task learning (MTL). Despite the inherent connection between diffusion models and MTL, there remains an unexplored area in designing neural architectures that explicitly incorporate MTL into the framework of diffusion models. In this paper, we present Denoising Task Routing (DTR), a simple add-on strategy for existing diffusion model architectures to establish distinct information pathways for individual tasks within a single architecture by selectively activating subsets of channels in the model. What makes DTR particularly compelling is its seamless integration of prior knowledge of denoising tasks into the framework: (1) Task Affinity: DTR activates similar channels for tasks at adjacent timesteps and shifts activated channels as sliding windows through timesteps, capitalizing on the inherent strong affinity between tasks at adjacent timesteps. (2) Task Weights: During the early stages (higher timesteps) of the denoising process, DTR assigns a greater number of task-specific channels, leveraging the insight that diffusion models prioritize reconstructing global structure and perceptually rich contents in earlier stages, and focus on simple noise removal in later stages. Our experiments reveal that DTR not only consistently boosts diffusion models' performance across different evaluation protocols without adding extra parameters but also accelerates training convergence. Finally, we show the complementarity between our architectural approach and existing MTL optimization techniques, providing a more complete view of MTL in the context of diffusion training. Significantly, by leveraging this complementarity, we attain matched performance of DiT-XL using the smaller DiT-L with a reduction in training iterations from 7M to 2M., Comment: ICLR 2024

Computerized Adaptive Testing (CAT) is a widely used, efficient test mode that adapts to the examinee's proficiency level in the test domain. CAT requires pre-trained item profiles, for CAT iteratively assesses the student real-time based on the registered items' profiles, and selects the next item to administer using candidate items' profiles. However, obtaining such item profiles is a costly process that involves gathering a large, dense item-response data, then training a diagnostic model on the collected data. In this paper, we explore the possibility of leveraging response data collected in the CAT service. We first show that this poses a unique challenge due to the inherent selection bias introduced by CAT, i.e., more proficient students will receive harder questions. Indeed, when naively training the diagnostic model using CAT response data, we observe that item profiles deviate significantly from the ground-truth. To tackle the selection bias issue, we propose the user-wise aggregate influence function method. Our intuition is to filter out users whose response data is heavily biased in an aggregate manner, as judged by how much perturbation the added data will introduce during parameter estimation. This way, we may enhance the performance of CAT while introducing minimal bias to the item profiles. We provide extensive experiments to demonstrate the superiority of our proposed method based on the three public datasets and one dataset that contains real-world CAT response data., Comment: CIKM 2023

Improvements to perovskite solar cells (PSCs) have focused on increasing their power conversion efficiency (PCE) and operational stability and maintaining high performance upon scale-up to module sizes. We report that replacing the commonly used mesoporous-titanium dioxide electron transport layer (ETL) with a thin layer of polyacrylic acid-stabilized tin(IV) oxide quantum dots (paa-QD-SnO2) on the compact-titanium dioxide enhanced light capture and largely suppressed nonradiative recombination at the ETL-perovskite interface. The use of paa-QD-SnO2 as electron-selective contact enabled PSCs (0.08 square centimeters) with a PCE of 25.7% (certified 25.4%) and high operational stability and facilitated the scale-up of the PSCs to larger areas. PCEs of 23.3, 21.7, and 20.6% were achieved for PSCs with active areas of 1, 20, and 64 square centimeters, respectively.

While polymer electrolyte membrane fuel cells (PEMFCs) have surged in popularity due to their low environmental impact and high efficiency, their susceptibility to degradation by in-situ generated peroxide and oxygen radical species has prevented their widespread adoption. To alleviate chemical attack on components of PEMFCs, particularly on polymer electrolyte membranes (PEMs), antioxidant approaches have been the subject of enormous interest as a key solution because they can directly scavenge and remove detrimental peroxide and oxygen radical species. However, a consequence is that long-term PEMFC device operation can cause undesirable adverse degradation of antioxidant additives provoked by the distinctive chemical/electrochemical environment of low pH, electric potential, water flux, and ion exchange/concentration gradient. Moreover, changes in the physical state such as migration, agglomeration, and dissolution of antioxidants by mechanical or chemical pressures are serious problems that gradually deteriorate antioxidant activity and capacity. This review presents current opportunities for and limitations to antioxidant therapy for durability enhancement in PEMs for electrochemical device applications. We also provide a summary of advanced synthetic design strategies and in-depth analyses of antioxidants regarding optimizing activity-stability factors. This review will bring new insight into the design to realization of ideal antioxidant nanostructures for PEMs and open up new opportunities for enhancing proliferation of durable PEMFCs.

Improvements to perovskite solar cells (PSCs) have focused on increasing their power conversion efficiency (PCE) and operational stability and maintaining high performance upon scale-up to module sizes. We report that replacing the commonly used mesoporous-titanium dioxide electron transport layer (ETL) with a thin layer of polyacrylic acid-stabilized tin(IV) oxide quantum dots (paa-QD-SnO2) on the compact-titanium dioxide enhanced light capture and largely suppressed nonradiative recombination at the ETL-perovskite interface. The use of paa-QD-SnO2 as electron-selective contact enabled PSCs (0.08 square centimeters) with a PCE of 25.7% (certified 25.4%) and high operational stability and facilitated the scale-up of the PSCs to larger areas. PCEs of 23.3, 21.7, and 20.6% were achieved for PSCs with active areas of 1, 20, and 64 square centimeters, respectively.

BACKGROUND: As the COVID-19 (Coronavirus disease 2019) pandemic is prolonged, psychological responses to the pandemic have changed, and a new scale to reflect these changes needs to be developed. In this study, we attempt to develop and validate the COVID-19 Impact Scale (CIS) to measure the psychological stress responses of the COVID-19 pandemic, including emotional responses and difficulty with activities of daily living. METHODS: We recruited 2152 participants. Participants completed the CIS, the Fear of COVID-19 Scale (FCV-19S), and other mental health related measures. The factor structure, reliability, and validity of the CIS were analyzed. In addition, the validity of the scale was confirmed by its relationships to the existing measures assessing fear of COVID-19, depression, anxiety, subjective well-being, and suicidal ideation. RESULTS: Using exploratory factor analysis (N1 = 1076), we derived a one-factor structure. In confirmatory factor analysis (N2 = 1076), the one-factor model showed good to excellent fitness. The CIS was positively correlated with depression, anxiety, suicidal ideation, fear of COVID-19 and negatively correlated with subjective well-being. The FCV-19S did not show significant correlations with subjective well-being or suicidal ideation, and FCV-19Ss explanatory powers on depression and anxiety were lower than those of the CIS. CONCLUSIONS: These results support that the CIS is a valid assessment of emotional problems and deterioration of the quality of life caused by the COVID-19 pandemic. Finally, the limitations of this study and future research directions are discussed.

Diffusion-based generative models have achieved remarkable success in image generation. Their guidance formulation allows an external model to plug-and-play control the generation process for various tasks without finetuning the diffusion model. However, the direct use of publicly available off-the-shelf models for guidance fails due to their poor performance on noisy inputs. For that, the existing practice is to fine-tune the guidance models with labeled data corrupted with noises. In this paper, we argue that this practice has limitations in two aspects: (1) performing on inputs with extremely various noises is too hard for a single guidance model; (2) collecting labeled datasets hinders scaling up for various tasks. To tackle the limitations, we propose a novel strategy that leverages multiple experts where each expert is specialized in a particular noise range and guides the reverse process of the diffusion at its corresponding timesteps. However, as it is infeasible to manage multiple networks and utilize labeled data, we present a practical guidance framework termed Practical Plug-And-Play (PPAP), which leverages parameter-efficient fine-tuning and data-free knowledge transfer. We exhaustively conduct ImageNet class conditional generation experiments to show that our method can successfully guide diffusion with small trainable parameters and no labeled data. Finally, we show that image classifiers, depth estimators, and semantic segmentation models can guide publicly available GLIDE through our framework in a plug-and-play manner. Our code is available at https://github.com/riiid/PPAP., Comment: CVPR 2023 camera-ready

We present a simple and versatile framework for evaluating ranked lists in terms of group fairness and relevance, where the groups (i.e., possible attribute values) can be either nominal or ordinal in nature. First, we demonstrate that, if the attribute set is binary, our framework can easily quantify the overall polarity of each ranked list. Second, by utilising an existing diversified search test collection and treating each intent as an attribute value, we demonstrate that our framework can handle soft group membership, and that our group fairness measures are highly correlated with both adhoc IR and diversified IR measures under this setting. Third, we demonstrate how our framework can quantify intersectional group fairness based on multiple attribute sets. We also show that the similarity function for comparing the achieved and target distributions over the attribute values should be chosen carefully.

Improvements to perovskite solar cells (PSCs) have focused on increasing their power conversion efficiency (PCE) and operational stability and maintaining high performance upon scale-up to module sizes. We report that replacing the commonly used mesoporous-titanium dioxide electron transport layer (ETL) with a thin layer of polyacrylic acid-stabilized tin(IV) oxide quantum dots (paa-QD-SnO2) on the compact-titanium dioxide enhanced light capture and largely suppressed nonradiative recombination at the ETL-perovskite interface. The use of paa-QD-SnO2 as electron-selective contact enabled PSCs (0.08 square centimeters) with a PCE of 25.7% (certified 25.4%) and high operational stability and facilitated the scale-up of the PSCs to larger areas. PCEs of 23.3, 21.7, and 20.6% were achieved for PSCs with active areas of 1, 20, and 64 square centimeters, respectively.

HUmic-LIke Substances (HULIS) consists of a significant fraction of water-soluble organic carbon (WSOC) and optically active brown carbon. Understanding seasonality in their abundance and sources is an important step to quantifying their impacts on air quality and climate. In this study, we characterized the seasonal variation of HULIS-C (the carbon component of HULIS) and identified primary and secondary sources contributing to HULIS-C at an urban site in Seoul, Korea by analyzing 131 PM2.5 samples collected over a year from October 2012 to September 2013. The HULIS-C in Seoul had an annual average of 2.0 mu g m(-3), and displayed a seasonality of highest abundance in the winter (2.7 +/- 1.3 mu g m(-3)) and the lowest in the summer (1.7 +/- 0.8 mu g m(-3)). Its fraction in WSOC reached up to 0.96 in the summer while remained relatively constant in the range of 0.4-0.6 in other seasons. Sources of HULIS-C were resolved using Positive Matrix Factorization (PMF) and checked using inter-species relationships between HILIS-C and aerosol components. Specifically, secondary processes including aging and heterogeneous reaction (26%) contributes to the year-round background concentration of HULIS-C and fresh biomass burning (38%) and incomplete combustion (16%) were the major sources of underlying seasonal variation. We also found aging process in the secondary process had an important role in HULIS-C formation and was a dominant contributor in the summer while heterogenous reaction contributed considerably in other seasons. It implies that the different secondary processes in forming HULIS should be considered when the radiative forcing of brown carbon is estimated. Because these processes can lead the different physicochemical properties of HULIS in aerosols.

HUmic-LIke Substances (HULIS) consists of a significant fraction of water-soluble organic carbon (WSOC) and optically active brown carbon. Understanding seasonality in their abundance and sources is an important step to quantifying their impacts on air quality and climate. In this study, we characterized the seasonal variation of HULIS-C (the carbon component of HULIS) and identified primary and secondary sources contributing to HULIS-C at an urban site in Seoul, Korea by analyzing 131 PM2.5 samples collected over a year from October 2012 to September 2013. The HULIS-C in Seoul had an annual average of 2.0 mu g m(-3), and displayed a seasonality of highest abundance in the winter (2.7 +/- 1.3 mu g m(-3)) and the lowest in the summer (1.7 +/- 0.8 mu g m(-3)). Its fraction in WSOC reached up to 0.96 in the summer while remained relatively constant in the range of 0.4-0.6 in other seasons. Sources of HULIS-C were resolved using Positive Matrix Factorization (PMF) and checked using inter-species relationships between HILIS-C and aerosol components. Specifically, secondary processes including aging and heterogeneous reaction (26%) contributes to the year-round background concentration of HULIS-C and fresh biomass burning (38%) and incomplete combustion (16%) were the major sources of underlying seasonal variation. We also found aging process in the secondary process had an important role in HULIS-C formation and was a dominant contributor in the summer while heterogenous reaction contributed considerably in other seasons. It implies that the different secondary processes in forming HULIS should be considered when the radiative forcing of brown carbon is estimated. Because these processes can lead the different physicochemical properties of HULIS in aerosols.

HUmic-LIke Substances (HULIS) consists of a significant fraction of water-soluble organic carbon (WSOC) and optically active brown carbon. Understanding seasonality in their abundance and sources is an important step to quantifying their impacts on air quality and climate. In this study, we characterized the seasonal variation of HULIS-C (the carbon component of HULIS) and identified primary and secondary sources contributing to HULIS-C at an urban site in Seoul, Korea by analyzing 131 PM2.5 samples collected over a year from October 2012 to September 2013. The HULIS-C in Seoul had an annual average of 2.0 mu g m(-3), and displayed a seasonality of highest abundance in the winter (2.7 +/- 1.3 mu g m(-3)) and the lowest in the summer (1.7 +/- 0.8 mu g m(-3)). Its fraction in WSOC reached up to 0.96 in the summer while remained relatively constant in the range of 0.4-0.6 in other seasons. Sources of HULIS-C were resolved using Positive Matrix Factorization (PMF) and checked using inter-species relationships between HILIS-C and aerosol components. Specifically, secondary processes including aging and heterogeneous reaction (26%) contributes to the year-round background concentration of HULIS-C and fresh biomass burning (38%) and incomplete combustion (16%) were the major sources of underlying seasonal variation. We also found aging process in the secondary process had an important role in HULIS-C formation and was a dominant contributor in the summer while heterogenous reaction contributed considerably in other seasons. It implies that the different secondary processes in forming HULIS should be considered when the radiative forcing of brown carbon is estimated. Because these processes can lead the different physicochemical properties of HULIS in aerosols.

Jae-Kwang Lim,1 Byunggeon Park,1 Jongmin Park,1 Keum-Ju Choi,2 Chi-Young Jung,2 Young Hwan Kim,3 Jin Young Kim,4 Sungjun Moon,5 Yong Hoon Lee,6 Jaehee Lee6 1Department of Radiology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea; 2Department of Internal Medicine, Daegu Catholic University School of Medicine, Daegu, Republic of Korea; 3Department of Radiology, Daegu Catholic University School of Medicine, Daegu, Republic of Korea; 4Department of Radiology, Dongsan Hospital, Keimyung University School of Medicine, Daegu, Republic of Korea; 5Department of Radiology, College of Medicine, Yeungnam University, Daegu, Republic of Korea; 6Department of Internal Medicine, School of Medicine, Kyungpook National University, Daegu, Republic of KoreaCorrespondence: Jaehee LeeDepartment of Internal Medicine, School of Medicine, Kyungpook National University, 680 Gukchaebosang-ro, Jung-gu, 41944, Daegu, Republic of KoreaTel +82-53-420-5536Fax +82-53-426-2046Email jaelee@knu.ac.krBackground: Chronic obstructive pulmonary disease (COPD) is considered a risk factor for poor outcomes in patients with coronavirus disease 2019 (COVID-19). However, data on the prognostic impact of radiological emphysema extent on patients with COVID-19 are limited. Thus, this study aimed to examine whether computed tomography (CT)-quantified emphysema score is associated with a worse clinical outcome in patients with COVID-19.Methods: Volumetric quantitative analyses of CT images were performed to obtain emphysema scores in COVID-19 patients admitted to four tertiary referral hospitals in Daegu, South Korea, between February 18 and March 25, 2020. Patients were divided into three groups according to emphysema score (emphysema score ≤ 1%, 1%< emphysema score ≤ 5%, and emphysema score > 5%).Results: A total of 146 patients with confirmed SARS-CoV-2 infection were included. The median emphysema score was 1.0% (interquartile range, 0.5– 1.8%). Eight patients (6%) had

We study gravitational perturbations of electrically charged black holes in (3+1)-dimensional Einstein-Born-Infeld gravity with a positive cosmological constant. For the axial perturbations, we obtain a set of decoupled Schrodinger-type equations, whose formal expressions, in terms of metric functions, are the same as those without cosmological constant, corresponding to the Regge-Wheeler equation in the proper limit. We compute the quasi-normal modes (QNMs) of the decoupled perturbations using the Schutz-Iyer-Will's WKB method. We discuss the stability of the charged black holes by investigating the dependence of quasi-normal frequencies on the parameters of the theory, correcting some errors in the literature. It is found that all the axial perturbations are stable for the cases where the WKB method applies. There are cases where the conventional WKB method does not apply, like the three-turning-points problem, so that a more generalized formalism is necessary for studying their QNMs and stabilities. We find that, for the degenerate horizons with the "point-like" horizons at the origin, the QNMs are quite long-lived, close to the quasi-resonance modes, in addition to the "frozen" QNMs for the Nariai-type horizons and the usual (short-lived) QNMs for the extremal black hole horizons. This is a genuine effect of the branch which does not have the general relativity limit. We also study the exact solution near the (charged) Nariai limit and find good agreements even far beyond the limit for the imaginary frequency parts., Comment: Matches published version

Glycosylation is a topic of intense current interest in the development of biopharmaceuticals because it is related to drug safety and efficacy. This work describes results of an interlaboratory study on the glycosylation of the Primary Sample (PS) of NISTmAb, a monoclonal antibody reference material. Seventy-six laboratories from industry, university, research, government, and hospital sectors in Europe, North America, Asia, and Australia submitted a total of 103 reports on glycan distributions. The principal objective of this study was to report and compare results for the full range of analytical methods presently used in the glycosylation analysis of mAbs. Therefore, participation was unrestricted, with laboratories choosing their own measurement techniques. Protein glycosylation was determined in various ways, including at the level of intact mAb, protein fragments, glycopeptides, or released glycans, using a wide variety of methods for derivatization, separation, identification, and quantification. Consequently, the diversity of results was enormous, with the number of glycan compositions identified by each laboratory ranging from 4 to 48. In total, one hundred sixteen glycan compositions were reported, of which 57 compositions could be assigned consensus abundance values. These consensus medians provide community-derived values for NISTmAb PS. Agreement with the consensus medians did not depend on the specific method or laboratory type. The study provides a view of the current state-of-the-art for biologic glycosylation measurement and suggests a clear need for harmonization of glycosylation analysis methods.

Glycosylation is a topic of intense current interest in the development of biopharmaceuticals because it is related to drug safety and efficacy. This work describes results of an interlaboratory study on the glycosylation of the Primary Sample (PS) of NISTmAb, a monoclonal antibody reference material. Seventy-six laboratories from industry, university, research, government, and hospital sectors in Europe, North America, Asia, and Australia submitted a total of 103 reports on glycan distributions. The principal objective of this study was to report and compare results for the full range of analytical methods presently used in the glycosylation analysis of mAbs. Therefore, participation was unrestricted, with laboratories choosing their own measurement techniques. Protein glycosylation was determined in various ways, including at the level of intact mAb, protein fragments, glycopeptides, or released glycans, using a wide variety of methods for derivatization, separation, identification, and quantification. Consequently, the diversity of results was enormous, with the number of glycan compositions identified by each laboratory ranging from 4 to 48. In total, one hundred sixteen glycan compositions were reported, of which 57 compositions could be assigned consensus abundance values. These consensus medians provide community-derived values for NISTmAb PS. Agreement with the consensus medians did not depend on the specific method or laboratory type. The study provides a view of the current state-of-the-art for biologic glycosylation measurement and suggests a clear need for harmonization of glycosylation analysis methods.

Cavitation is a common damage mechanism in soft solids. Here, we study this using a phase separation technique in stretched, elastic solids to controllably nucleate and grow small cavities by several orders of magnitude. The ability to make stable cavities of different sizes, as well as the huge range of accessible strains, allows us to systematically study the early stages of cavity expansion. Cavities grow in a scale-free manner, accompanied by irreversible bond breakage that is distributed around the growing cavity rather than being localized to a crack tip. Furthermore, cavities appear to grow at constant driving pressure. This has strong analogies with the plasticity that occurs surrounding a growing void in ductile metals. In particular, we find that, although elastomers are normally considered as brittle materials, small-scale cavity expansion is more like a ductile process. Our results have broad implications for understanding and controlling failure in soft solids., Swiss National Science foundation (grant 200021-172827)., National Science Foundation (grant no. CMMI-1537087), MOTIE in Korea, under the Fostering Global Talents for Innovative Growth Program supervised by the KIAT (grant no. P0008746)

We study the matter perturbations of a new AdS wormhole in (3+1)-dimensional Einstein-Born-Infeld gravity, called "natural wormhole", which does not require exotic matters. We discuss the stability of the perturbations by numerically computing the quasi-normal modes (QNMs) of a massive scalar field in the wormhole background. We investigate the dependence of quasi-normal frequencies on the mass of scalar field as well as other parameters of the wormhole. It is found that the perturbations are always stable for the wormhole geometry which has the general relativity (GR) limit when the scalar field mass m satisfies a certain, tachyonic mass bound m^2 > m^2_* with m^2_* < 0, analogous to the Breitenlohner-Freedman (BF) bound in the global-AdS space, m^2_BF = 3 Lambda/4. It is also found that the BF-like bound m^2_* shifts by the changes of the cosmological constant Lambda or angular-momentum number l, with a level crossing between the lowest complex and pure-imaginary modes for zero angular momentum l = 0. Furthermore, it is found that the unstable modes can also have oscillatory parts as well as non-oscillatory parts depending on whether the real and imaginary parts of frequencies are dependent on each other or not, contrary to arguments in the literature. For wormhole geometries which do not have the GR limit, the BF-like bound does not occur and the perturbations are stable for arbitrary tachyonic and non-tachyonic masses, up to a critical mass m^2_c > 0 where the perturbations are completely frozen., Comment: Added comments and references, Accepted in EPJC

We study the matter perturbations of a new AdS wormhole in (3+1)-dimensional Einstein-Born-Infeld gravity, called "natural wormhole", which does not require exotic matters. We discuss the stability of the perturbations by numerically computing the quasi-normal modes (QNMs) of a massive scalar field in the wormhole background. We investigate the dependence of quasi-normal frequencies on the mass of scalar field as well as other parameters of the wormhole. It is found that the perturbations are always stable for the wormhole geometry which has the general relativity (GR) limit when the scalar field mass m satisfies a certain, tachyonic mass bound m^2 > m^2_* with m^2_* < 0, analogous to the Breitenlohner-Freedman (BF) bound in the global-AdS space, m^2_BF = 3 Lambda/4. It is also found that the BF-like bound m^2_* shifts by the changes of the cosmological constant Lambda or angular-momentum number l, with a level crossing between the lowest complex and pure-imaginary modes for zero angular momentum l = 0. Furthermore, it is found that the unstable modes can also have oscillatory parts as well as non-oscillatory parts depending on whether the real and imaginary parts of frequencies are dependent on each other or not, contrary to arguments in the literature. For wormhole geometries which do not have the GR limit, the BF-like bound does not occur and the perturbations are stable for arbitrary tachyonic and non-tachyonic masses, up to a critical mass m^2_c > 0 where the perturbations are completely frozen., Comment: Added comments and references, Accepted in EPJC

In this paper, we study an interference avoidance scenario in the presence of a smart interferer which can rapidly observe the transmit power of a backscatter wireless sensor network (WSN) and effectively interrupt backscatter signals. We consider a power control with a sub-channel allocation to avoid interference attacks and a time-switching ratio for backscattering and RF energy harvesting in backscatter WSNs. We formulate the problem based on a Stackelberg game theory and compute the optimal transmit power, time-switching ratio, and sub-channel allocation parameter to maximize a utility function against the smart interference. We propose two algorithms for the utility maximization using Lagrangian dual decomposition for the backscatter WSN and the smart interference to prove the existence of the Stackelberg equilibrium. Numerical results show that the proposed algorithms effectively maximize the utility, compared to that of the algorithm based on the Nash game, so as to overcome smart interference in backscatter communications., Comment: 13 pages

We study a new approach for the wormhole construction in Einstein-Born-Infeld gravity, which does not require exotic matters in the Einstein equation. The Born-Infeld field equation is not modified from "coordinate independent" conditions of continuous metric tensor and its derivatives, even though the Born-Infeld fields have discontinuities in their derivatives at the throat in general. We study the relation of the newly introduced conditions with the usual continuity equation for the energy-momentum tensor and the gravitational Bianchi identity. We find that there is no violation of energy conditions for the Born-Infeld fields contrary to the usual approaches. The exoticity of energy-momentum tensor is not essential for sustaining wormholes. Some open problems are discussed., Comment: Minor revision to improve the clarity, Corrected typos, Added reference and footnote

We study a new approach for the wormhole construction in Einstein-Born-Infeld gravity, which does not require exotic matters in the Einstein equation. The Born-Infeld field equation is not modified from "coordinate independent" conditions of continuous metric tensor and its derivatives, even though the Born-Infeld fields have discontinuities in their derivatives at the throat in general. We study the relation of the newly introduced conditions with the usual continuity equation for the energy-momentum tensor and the gravitational Bianchi identity. We find that there is no violation of energy conditions for the Born-Infeld fields contrary to the usual approaches. The exoticity of energy-momentum tensor is not essential for sustaining wormholes. Some open problems are discussed., Comment: Minor revision to improve the clarity, Corrected typos, Added reference and footnote

A Markovian battery model is proposed to provide the variation of energy states for energy harvesting (EH) secondary users (SUs) in the EH cognitive radio networks (CRN). Based on the proposed battery model, we derive the packet loss probability in the EH SUs due to sensing inaccuracy and energy outage. With the proposed analysis, the packet loss probability can easily be predicted and utilized to optimize the transmission policy (i.e., opportunities for successful transmission and EH) of EH SUs to improve their throughput. Especially, the proposed method can be applied to upper layer (scheduling and routing) optimization. To this end, we validate the proposed analysis through Monte-Carlo simulation and show an agreement between the analysis and simulations results.

The endolymphatic sac (ES) is a cystic organ that is a part of the inner ear and is connected to the cochlea and vestibule. The ES is thought to be involved in inner ear ion homeostasis and fluid volume regulation for the maintenance of hearing and balance function. Many ion channels, transporters, and exchangers have been identified in the ES luminal epithelium, mainly in animal studies, but there has been no functional study investigating ion transport using human ES tissue. We designed the first functional experiments on electrogenic transport in human ES and investigated the contribution of K(+) channels in the electrogenic transport, which has been rarely identified, even in animal studies, using electrophysiological/pharmacological and molecular biological methods. As a result, we identified functional and molecular evidence for the essential participation of K(+) channels in the electrogenic transport of human ES epithelium. The identified K(+) channels involved in the electrogenic transport were KCNN2, KCNJ14, KCNK2, and KCNK6, and the K(+) transports via those channels are thought to play an important role in the maintenance of the unique ionic milieu of the inner ear fluid.

Hard and soft structural composites found in biology provide inspiration for the design of advanced synthetic materials. Many examples of bio-inspired hard materials can be found in the literature; far less attention has been devoted to soft systems. Here we introduce deterministic routes to low-modulus thin film materials with stress/strain responses that can be tailored precisely to match the non-linear properties of biological tissues, with application opportunities that range from soft biomedical devices to constructs for tissue engineering. The approach combines a low-modulus matrix with an open, stretchable network as a structural reinforcement that can yield classes of composites with a wide range of desired mechanical responses, including anisotropic, spatially heterogeneous, hierarchical and self-similar designs. Demonstrative application examples in thin, skin-mounted electrophysiological sensors with mechanics precisely matched to the human epidermis and in soft, hydrogel-based vehicles for triggered drug release suggest their broad potential uses in biomedical devices.

UnlabelledOrganic-inorganic hybrid perovskite materials offer the potential for realization of low-cost and flexible next-generation solar cells fabricated by low-temperature solution processing. Although efficiencies of perovskite solar cells have dramatically improved up to 19% within the past 5 years, there is still considerable room for further improvement in device efficiency and stability through development of novel materials and device architectures. Here we demonstrate that inverted-type perovskite solar cells with pH-neutral and low-temperature solution-processable conjugated polyelectrolyte as the hole transport layer (instead of acidicPedotPSS) exhibit a device efficiency of over 12% and improved device stability in air. As an alternative toPedotPSS, this work is the first report on the use of an organic hole transport material that enables the formation of uniform perovskite films with complete surface coverage and the demonstration of efficient, stable perovskite/fullerene planar heterojunction solar cells.

Preparation of well-interconnected TiO2 electrodes at low temperature is critical for the fabrication of highly efficient dye-sensitized solar cells (DSCs) on plastic substrates. Herein we explore a synergistic approach using a combination of chemical and physical sintering. We formulate a binder-free TiO2 paste based on “nanoglue” as the chemical sintering agent, and use it to construct a photoelectrode on plastic by low-temperature physical compression to further improve the connectivity of TiO2 films. We systematically investigated the factors affecting the photovoltaic performance and found the conditions to achieve electron diffusion lengths as long as 25 mm and charge collection efficiencies as high as 95%, as electrochemical impedance spectroscopy measurements indicate. We apply this approach to obtain a DSC deposited on plastic displaying 6.4% power conversion efficiency based on commercial P25 titania particles

Preparation of well-interconnected TiO2 electrodes at low temperature is critical for the fabrication of highly efficient dye-sensitized solar cells (DSCs) on plastic substrates. Herein we explore a synergistic approach using a combination of chemical and physical sintering. We formulate a binder-free TiO2 paste based on “nanoglue” as the chemical sintering agent, and use it to construct a photoelectrode on plastic by low-temperature physical compression to further improve the connectivity of TiO2 films. We systematically investigated the factors affecting the photovoltaic performance and found the conditions to achieve electron diffusion lengths as long as 25 mm and charge collection efficiencies as high as 95%, as electrochemical impedance spectroscopy measurements indicate. We apply this approach to obtain a DSC deposited on plastic displaying 6.4% power conversion efficiency based on commercial P25 titania particles

Metallic glasses exhibit many attractive attributes such as outstanding mechanical, magnetic, and chemical properties. Due to the absence of crystal defects, metallic glasses display remarkable mechanical properties including higher specific strength than crystalline alloys, high hardness and larger fracture resistance than ceramics. The technological breakthrough of metallic glasses, however, has been greatly hindered by the limited plastic strain to failure. Thus, several strategies have been employed to improve the intrinsic and extrinsic effects on the flow behavior of metallic glasses with respect to their fracture toughness and overall plastic strain. One of the suggested strategies is the production of a composite consisting of the brittle metallic glass along with a ductile second phase that either acts as an active carrier of plastic strain or passively enhances the multiplication of shear bands via shear-band splitting . Another approach for increasing plastic deformation consists of introducing pores as a gaseous second phase into the material. The pores are similarly effective in delaying catastrophic failure resulting from shear band localization. In metallic glasses with high porosity, propagation of shear bands can even become stable, enabling macroscopic compressive strains of more than 80 % without fracture. In this thesis, Ni59Zr20Ti16Si2Sn3 glass and its composites have been fabricated using mechanical milling and consolidation by hot pressing followed by extrusion of Ni59Zr20Ti16Si2Sn3 metallic glass powder or Ni59Zr20Ti16Si2Sn3 metallic glass powder reinforced with 40 vol.% of brass particles to obtained bulk composite materials with high strength and enhanced compressive plasticity and to generate porous structure in Ni59Zr20Ti16Si2Sn3 metallic glass using selective dissolution. The brass–glass powder mixtures to be consolidated were prepared using two different approaches: manual blending and ball milling to properly vary size and morphology o, Metallische Gläser weisen viele attraktive mechanische, magnetische und chemische Eigenschaften auf. Aufgrund der fehlenden Kristallstruktur zeigen metallische Gläser bemerkenswerte mechanische Eigenschaften, einschließlich höherer spezifischer Festigkeit, höherer Härte und größerer Bruchfestigkeit als Keramik. Der technologischen Durchbruch metallischer Gläser wird jedoch bis heute stark von ihremspröden Bruchverhalten behindert. Deshalb wurden verschiedene Herstellungsverfahren entwirkt, um sowohl die plastische Verformung der metallischer Massivgläser zu erhöhen, als auch um die mechanischen Eigenschaften generell zu verbessern. Eine mögliche Methode, zur Erhöhung der Plastizität und zur Beeinflussung der mechanischen Eigenschaften der metallischen Gläser ist der Einbau zweiter Phasen, wie z.B. durch Fremdpartikel Verstärkung oder Poren in Kompositen. Die Scherband bewegung wird durch die Wechselwirkung mit zweiten Phasen behindert, und gleichzeitig werden durch die in den Grenzflächen entstehenden Spannungsspitzen zwischen der zweiten Phase und der Matrix neue Scherbänder initiert. Dies führt zur Bildung einer Vielzahl von Scherbändern, was eine höhere plastische Dehnung zur Folge hat, da die Deformationsenergie auf ein größeres Volumen verteilt wird. In der vorliegenden Arbeit wurden Ni59Zr20Ti16Si2Sn3 Massivglas und mit Messing- verstärkte Komposite durch Kugelmahlen und Heißpressen mit anschließender Extrusion von Ni59Zr20Ti16Si2Sn3 Pulver oder Ni59Zr20Ti16Si2Sn3 Pulver mit 40 vol.% Messing Partikeln hergestellt. Neben der Herstellung der Ni59Zr20Ti16Si2Sn3 Komposite mit Messing Partikeln, wurden auch Ni59Zr20Ti16Si2Sn3 Komposite mit definierter Porösität durch die selektive Auflösung der zweiten Phase erzeugt. Die verwendete Mischung von Messing und metallischem Glaspulver wurde über zwei verschiedene Ansätzen hergestellt: die Pulver wurden manuell gemischt oder gemahlen, um die optimale Größe und Morphologie der zweiten Phase in den Komositen zu erzeugen. D

Metallic glasses exhibit many attractive attributes such as outstanding mechanical, magnetic, and chemical properties. Due to the absence of crystal defects, metallic glasses display remarkable mechanical properties including higher specific strength than crystalline alloys, high hardness and larger fracture resistance than ceramics. The technological breakthrough of metallic glasses, however, has been greatly hindered by the limited plastic strain to failure. Thus, several strategies have been employed to improve the intrinsic and extrinsic effects on the flow behavior of metallic glasses with respect to their fracture toughness and overall plastic strain. One of the suggested strategies is the production of a composite consisting of the brittle metallic glass along with a ductile second phase that either acts as an active carrier of plastic strain or passively enhances the multiplication of shear bands via shear-band splitting . Another approach for increasing plastic deformation consists of introducing pores as a gaseous second phase into the material. The pores are similarly effective in delaying catastrophic failure resulting from shear band localization. In metallic glasses with high porosity, propagation of shear bands can even become stable, enabling macroscopic compressive strains of more than 80 % without fracture. In this thesis, Ni59Zr20Ti16Si2Sn3 glass and its composites have been fabricated using mechanical milling and consolidation by hot pressing followed by extrusion of Ni59Zr20Ti16Si2Sn3 metallic glass powder or Ni59Zr20Ti16Si2Sn3 metallic glass powder reinforced with 40 vol.% of brass particles to obtained bulk composite materials with high strength and enhanced compressive plasticity and to generate porous structure in Ni59Zr20Ti16Si2Sn3 metallic glass using selective dissolution. The brass–glass powder mixtures to be consolidated were prepared using two different approaches: manual blending and ball milling to properly vary size and morphology o, Metallische Gläser weisen viele attraktive mechanische, magnetische und chemische Eigenschaften auf. Aufgrund der fehlenden Kristallstruktur zeigen metallische Gläser bemerkenswerte mechanische Eigenschaften, einschließlich höherer spezifischer Festigkeit, höherer Härte und größerer Bruchfestigkeit als Keramik. Der technologischen Durchbruch metallischer Gläser wird jedoch bis heute stark von ihremspröden Bruchverhalten behindert. Deshalb wurden verschiedene Herstellungsverfahren entwirkt, um sowohl die plastische Verformung der metallischer Massivgläser zu erhöhen, als auch um die mechanischen Eigenschaften generell zu verbessern. Eine mögliche Methode, zur Erhöhung der Plastizität und zur Beeinflussung der mechanischen Eigenschaften der metallischen Gläser ist der Einbau zweiter Phasen, wie z.B. durch Fremdpartikel Verstärkung oder Poren in Kompositen. Die Scherband bewegung wird durch die Wechselwirkung mit zweiten Phasen behindert, und gleichzeitig werden durch die in den Grenzflächen entstehenden Spannungsspitzen zwischen der zweiten Phase und der Matrix neue Scherbänder initiert. Dies führt zur Bildung einer Vielzahl von Scherbändern, was eine höhere plastische Dehnung zur Folge hat, da die Deformationsenergie auf ein größeres Volumen verteilt wird. In der vorliegenden Arbeit wurden Ni59Zr20Ti16Si2Sn3 Massivglas und mit Messing- verstärkte Komposite durch Kugelmahlen und Heißpressen mit anschließender Extrusion von Ni59Zr20Ti16Si2Sn3 Pulver oder Ni59Zr20Ti16Si2Sn3 Pulver mit 40 vol.% Messing Partikeln hergestellt. Neben der Herstellung der Ni59Zr20Ti16Si2Sn3 Komposite mit Messing Partikeln, wurden auch Ni59Zr20Ti16Si2Sn3 Komposite mit definierter Porösität durch die selektive Auflösung der zweiten Phase erzeugt. Die verwendete Mischung von Messing und metallischem Glaspulver wurde über zwei verschiedene Ansätzen hergestellt: die Pulver wurden manuell gemischt oder gemahlen, um die optimale Größe und Morphologie der zweiten Phase in den Komositen zu erzeugen. D

Organic-inorganic hybrid perovskite materials offer the potential for realization of low-cost and flexible next-generation solar cells fabricated by low-temperature solution processing. Although efficiencies of perovskite solar cells have dramatically improved up to 19% within the past 5 years, there is still considerable room for further improvement in device efficiency and stability through development of novel materials and device architectures. Here we demonstrate that inverted-type perovskite solar cells with pH-neutral and low-temperature solution-processable conjugated polyelectrolyte as the hole transport layer (instead of acidicPedotPSS) exhibit a device efficiency of over 12% and improved device stability in air. As an alternative toPedotPSS, this work is the first report on the use of an organic hole transport material that enables the formation of uniform perovskite films with complete surface coverage and the demonstration of efficient, stable perovskite/fullerene planar heterojunction solar cells.

Hard and soft structural composites found in biology provide inspiration for the design of advanced synthetic materials. Many examples of bio-inspired hard materials can be found in the literature; far less attention has been devoted to soft systems. Here we introduce deterministic routes to low-modulus thin film materials with stress/strain responses that can be tailored precisely to match the non-linear properties of biological tissues, with application opportunities that range from soft biomedical devices to constructs for tissue engineering. The approach combines a low-modulus matrix with an open, stretchable network as a structural reinforcement that can yield classes of composites with a wide range of desired mechanical responses, including anisotropic, spatially heterogeneous, hierarchical and self-similar designs. Demonstrative application examples in thin, skin-mounted electrophysiological sensors with mechanics precisely matched to the human epidermis and in soft, hydrogel-based vehicles for triggered drug release suggest their broad potential uses in biomedical devices.

Preparation of well-interconnected TiO2 electrodes at low temperature is critical for the fabrication of highly efficient dye-sensitized solar cells (DSCs) on plastic substrates. Herein we explore a synergistic approach using a combination of chemical and physical sintering. We formulate a binder-free TiO2 paste based on “nanoglue” as the chemical sintering agent, and use it to construct a photoelectrode on plastic by low-temperature physical compression to further improve the connectivity of TiO2 films. We systematically investigated the factors affecting the photovoltaic performance and found the conditions to achieve electron diffusion lengths as long as 25 mm and charge collection efficiencies as high as 95%, as electrochemical impedance spectroscopy measurements indicate. We apply this approach to obtain a DSC deposited on plastic displaying 6.4% power conversion efficiency based on commercial P25 titania particles

Organic-inorganic hybrid perovskite materials offer the potential for realization of low-cost and flexible next-generation solar cells fabricated by low-temperature solution processing. Although efficiencies of perovskite solar cells have dramatically improved up to 19% within the past 5 years, there is still considerable room for further improvement in device efficiency and stability through development of novel materials and device architectures. Here we demonstrate that inverted-type perovskite solar cells with pH-neutral and low-temperature solution-processable conjugated polyelectrolyte as the hole transport layer (instead of acidicPedotPSS) exhibit a device efficiency of over 12% and improved device stability in air. As an alternative toPedotPSS, this work is the first report on the use of an organic hole transport material that enables the formation of uniform perovskite films with complete surface coverage and the demonstration of efficient, stable perovskite/fullerene planar heterojunction solar cells.

The endolymphatic sac (ES) is a cystic organ that is a part of the inner ear and is connected to the cochlea and vestibule. The ES is thought to be involved in inner ear ion homeostasis and fluid volume regulation for the maintenance of hearing and balance function. Many ion channels, transporters, and exchangers have been identified in the ES luminal epithelium, mainly in animal studies, but there has been no functional study investigating ion transport using human ES tissue. We designed the first functional experiments on electrogenic transport in human ES and investigated the contribution of K(+) channels in the electrogenic transport, which has been rarely identified, even in animal studies, using electrophysiological/pharmacological and molecular biological methods. As a result, we identified functional and molecular evidence for the essential participation of K(+) channels in the electrogenic transport of human ES epithelium. The identified K(+) channels involved in the electrogenic transport were KCNN2, KCNJ14, KCNK2, and KCNK6, and the K(+) transports via those channels are thought to play an important role in the maintenance of the unique ionic milieu of the inner ear fluid.

Metallic glasses exhibit many attractive attributes such as outstanding mechanical, magnetic, and chemical properties. Due to the absence of crystal defects, metallic glasses display remarkable mechanical properties including higher specific strength than crystalline alloys, high hardness and larger fracture resistance than ceramics. The technological breakthrough of metallic glasses, however, has been greatly hindered by the limited plastic strain to failure. Thus, several strategies have been employed to improve the intrinsic and extrinsic effects on the flow behavior of metallic glasses with respect to their fracture toughness and overall plastic strain. One of the suggested strategies is the production of a composite consisting of the brittle metallic glass along with a ductile second phase that either acts as an active carrier of plastic strain or passively enhances the multiplication of shear bands via shear-band splitting . Another approach for increasing plastic deformation consists of introducing pores as a gaseous second phase into the material. The pores are similarly effective in delaying catastrophic failure resulting from shear band localization. In metallic glasses with high porosity, propagation of shear bands can even become stable, enabling macroscopic compressive strains of more than 80 % without fracture. In this thesis, Ni59Zr20Ti16Si2Sn3 glass and its composites have been fabricated using mechanical milling and consolidation by hot pressing followed by extrusion of Ni59Zr20Ti16Si2Sn3 metallic glass powder or Ni59Zr20Ti16Si2Sn3 metallic glass powder reinforced with 40 vol.% of brass particles to obtained bulk composite materials with high strength and enhanced compressive plasticity and to generate porous structure in Ni59Zr20Ti16Si2Sn3 metallic glass using selective dissolution. The brass–glass powder mixtures to be consolidated were prepared using two different approaches: manual blending and ball milling to properly vary size and morphology o, Metallische Gläser weisen viele attraktive mechanische, magnetische und chemische Eigenschaften auf. Aufgrund der fehlenden Kristallstruktur zeigen metallische Gläser bemerkenswerte mechanische Eigenschaften, einschließlich höherer spezifischer Festigkeit, höherer Härte und größerer Bruchfestigkeit als Keramik. Der technologischen Durchbruch metallischer Gläser wird jedoch bis heute stark von ihremspröden Bruchverhalten behindert. Deshalb wurden verschiedene Herstellungsverfahren entwirkt, um sowohl die plastische Verformung der metallischer Massivgläser zu erhöhen, als auch um die mechanischen Eigenschaften generell zu verbessern. Eine mögliche Methode, zur Erhöhung der Plastizität und zur Beeinflussung der mechanischen Eigenschaften der metallischen Gläser ist der Einbau zweiter Phasen, wie z.B. durch Fremdpartikel Verstärkung oder Poren in Kompositen. Die Scherband bewegung wird durch die Wechselwirkung mit zweiten Phasen behindert, und gleichzeitig werden durch die in den Grenzflächen entstehenden Spannungsspitzen zwischen der zweiten Phase und der Matrix neue Scherbänder initiert. Dies führt zur Bildung einer Vielzahl von Scherbändern, was eine höhere plastische Dehnung zur Folge hat, da die Deformationsenergie auf ein größeres Volumen verteilt wird. In der vorliegenden Arbeit wurden Ni59Zr20Ti16Si2Sn3 Massivglas und mit Messing- verstärkte Komposite durch Kugelmahlen und Heißpressen mit anschließender Extrusion von Ni59Zr20Ti16Si2Sn3 Pulver oder Ni59Zr20Ti16Si2Sn3 Pulver mit 40 vol.% Messing Partikeln hergestellt. Neben der Herstellung der Ni59Zr20Ti16Si2Sn3 Komposite mit Messing Partikeln, wurden auch Ni59Zr20Ti16Si2Sn3 Komposite mit definierter Porösität durch die selektive Auflösung der zweiten Phase erzeugt. Die verwendete Mischung von Messing und metallischem Glaspulver wurde über zwei verschiedene Ansätzen hergestellt: die Pulver wurden manuell gemischt oder gemahlen, um die optimale Größe und Morphologie der zweiten Phase in den Komositen zu erzeugen. D

Preparation of well-interconnected TiO2 electrodes at low temperature is critical for the fabrication of highly efficient dye-sensitized solar cells (DSCs) on plastic substrates. Herein we explore a synergistic approach using a combination of chemical and physical sintering. We formulate a binder-free TiO2 paste based on “nanoglue” as the chemical sintering agent, and use it to construct a photoelectrode on plastic by low-temperature physical compression to further improve the connectivity of TiO2 films. We systematically investigated the factors affecting the photovoltaic performance and found the conditions to achieve electron diffusion lengths as long as 25 mm and charge collection efficiencies as high as 95%, as electrochemical impedance spectroscopy measurements indicate. We apply this approach to obtain a DSC deposited on plastic displaying 6.4% power conversion efficiency based on commercial P25 titania particles

Preparation of well-interconnected TiO2 electrodes at low temperature is critical for the fabrication of highly efficient dye-sensitized solar cells (DSCs) on plastic substrates. Herein we explore a synergistic approach using a combination of chemical and physical sintering. We formulate a binder-free TiO2 paste based on “nanoglue” as the chemical sintering agent, and use it to construct a photoelectrode on plastic by low-temperature physical compression to further improve the connectivity of TiO2 films. We systematically investigated the factors affecting the photovoltaic performance and found the conditions to achieve electron diffusion lengths as long as 25 mm and charge collection efficiencies as high as 95%, as electrochemical impedance spectroscopy measurements indicate. We apply this approach to obtain a DSC deposited on plastic displaying 6.4% power conversion efficiency based on commercial P25 titania particles

Metallic glasses exhibit many attractive attributes such as outstanding mechanical, magnetic, and chemical properties. Due to the absence of crystal defects, metallic glasses display remarkable mechanical properties including higher specific strength than crystalline alloys, high hardness and larger fracture resistance than ceramics. The technological breakthrough of metallic glasses, however, has been greatly hindered by the limited plastic strain to failure. Thus, several strategies have been employed to improve the intrinsic and extrinsic effects on the flow behavior of metallic glasses with respect to their fracture toughness and overall plastic strain. One of the suggested strategies is the production of a composite consisting of the brittle metallic glass along with a ductile second phase that either acts as an active carrier of plastic strain or passively enhances the multiplication of shear bands via shear-band splitting . Another approach for increasing plastic deformation consists of introducing pores as a gaseous second phase into the material. The pores are similarly effective in delaying catastrophic failure resulting from shear band localization. In metallic glasses with high porosity, propagation of shear bands can even become stable, enabling macroscopic compressive strains of more than 80 % without fracture. In this thesis, Ni59Zr20Ti16Si2Sn3 glass and its composites have been fabricated using mechanical milling and consolidation by hot pressing followed by extrusion of Ni59Zr20Ti16Si2Sn3 metallic glass powder or Ni59Zr20Ti16Si2Sn3 metallic glass powder reinforced with 40 vol.% of brass particles to obtained bulk composite materials with high strength and enhanced compressive plasticity and to generate porous structure in Ni59Zr20Ti16Si2Sn3 metallic glass using selective dissolution. The brass–glass powder mixtures to be consolidated were prepared using two different approaches: manual blending and ball milling to properly vary size and morphology o, Metallische Gläser weisen viele attraktive mechanische, magnetische und chemische Eigenschaften auf. Aufgrund der fehlenden Kristallstruktur zeigen metallische Gläser bemerkenswerte mechanische Eigenschaften, einschließlich höherer spezifischer Festigkeit, höherer Härte und größerer Bruchfestigkeit als Keramik. Der technologischen Durchbruch metallischer Gläser wird jedoch bis heute stark von ihremspröden Bruchverhalten behindert. Deshalb wurden verschiedene Herstellungsverfahren entwirkt, um sowohl die plastische Verformung der metallischer Massivgläser zu erhöhen, als auch um die mechanischen Eigenschaften generell zu verbessern. Eine mögliche Methode, zur Erhöhung der Plastizität und zur Beeinflussung der mechanischen Eigenschaften der metallischen Gläser ist der Einbau zweiter Phasen, wie z.B. durch Fremdpartikel Verstärkung oder Poren in Kompositen. Die Scherband bewegung wird durch die Wechselwirkung mit zweiten Phasen behindert, und gleichzeitig werden durch die in den Grenzflächen entstehenden Spannungsspitzen zwischen der zweiten Phase und der Matrix neue Scherbänder initiert. Dies führt zur Bildung einer Vielzahl von Scherbändern, was eine höhere plastische Dehnung zur Folge hat, da die Deformationsenergie auf ein größeres Volumen verteilt wird. In der vorliegenden Arbeit wurden Ni59Zr20Ti16Si2Sn3 Massivglas und mit Messing- verstärkte Komposite durch Kugelmahlen und Heißpressen mit anschließender Extrusion von Ni59Zr20Ti16Si2Sn3 Pulver oder Ni59Zr20Ti16Si2Sn3 Pulver mit 40 vol.% Messing Partikeln hergestellt. Neben der Herstellung der Ni59Zr20Ti16Si2Sn3 Komposite mit Messing Partikeln, wurden auch Ni59Zr20Ti16Si2Sn3 Komposite mit definierter Porösität durch die selektive Auflösung der zweiten Phase erzeugt. Die verwendete Mischung von Messing und metallischem Glaspulver wurde über zwei verschiedene Ansätzen hergestellt: die Pulver wurden manuell gemischt oder gemahlen, um die optimale Größe und Morphologie der zweiten Phase in den Komositen zu erzeugen. D

Preparation of well-interconnected TiO2 electrodes at low temperature is critical for the fabrication of highly efficient dye-sensitized solar cells (DSCs) on plastic substrates. Herein we explore a synergistic approach using a combination of chemical and physical sintering. We formulate a binder-free TiO2 paste based on “nanoglue” as the chemical sintering agent, and use it to construct a photoelectrode on plastic by low-temperature physical compression to further improve the connectivity of TiO2 films. We systematically investigated the factors affecting the photovoltaic performance and found the conditions to achieve electron diffusion lengths as long as 25 mm and charge collection efficiencies as high as 95%, as electrochemical impedance spectroscopy measurements indicate. We apply this approach to obtain a DSC deposited on plastic displaying 6.4% power conversion efficiency based on commercial P25 titania particles

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2012., This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections., Cataloged from student submitted PDF version of thesis., Includes bibliographical references., Ligand-stabilized nanoparticles (NPs) assembled into long-range ordered arrays, also known as "nanoparticle supracrystals (NPSCs)", are expected to provide a powerful general platform for designing new types of solids. In particular, the NPs are themselves self-assembled structures consisting of a core and a self-assembled monolayer of ligand molecules surrounding it. The self-assembled structure of the NPs themselves determines the structure of the self-assembled supracrystals. Ligands are of special interest in this respect, because it is an important component for the NP system which play a major role in the design of self-assembly of the complex matter and also provide a powerful entry into the supracrystal engineering. The increasing ability to control the way in which ligand molecules associate gives means for the designed generation of supraparticle architectures in the self-assembly. In spite of this, elucidation of how the ligands play a role in affecting the structural behavior of NPSCs remains largely unrevealed. In this thesis, the effect of ligands for the two dimensional (2D) self-assembled NPSCs structure was investigated. The key materials advancement that enables this work is that we have been able to synthesize monodisperse gold NPs of same core size but different ligand molecules. Additionally, a new method for monolayer film processing has been developed to prepare the 2D NPSCs, based on a Langmuir assembly through successive compression cycles. Importantly, as there is little effect exhibited by solvent interactions in the NPs structure obtained from this approach, the corresponding NPs structural variation in this work is truly driven by the different ligand interactions in NPSCs. Specifically, we show that such ligand interactions have direct consequences on the ordering and symmetry of the assembled NPSCs structures. Here, we report on a set of NPSC arrays in which small changes in either the NP ligand environment or the ligand configuration, by Jin Young Kim., Ph.D.