Diffusion Brush: A Latent Diffusion Model-based Editing Tool for AI-generated Images

Text-to-image generative models have made remarkable advancements in generating high-quality images. However, generated images often contain undesirable artifacts or other errors due to model limitations. Existing techniques to fine-tune generated images are time-consuming (manual editing), produce poorly-integrated results (inpainting), or result in unexpected changes across the entire image (variation selection and prompt fine-tuning). In this work, we present Diffusion Brush, a Latent Diffusion Model-based (LDM) tool to efficiently fine-tune desired regions within an AI-synthesized image. Our method introduces new random noise patterns at targeted regions during the reverse diffusion process, enabling the model to efficiently make changes to the specified regions while preserving the original context for the rest of the image. We evaluate our method's usability and effectiveness through a user study with artists, comparing our technique against other state-of-the-art image inpainting techniques and editing software for fine-tuning AI-generated imagery

Developing algorithms for the analysis of retinal Optical Coherence Tomography images

Vision loss, with a prevalence loss greater than 42 million in the United States is one of the major challenges of today's health-care industry and medical science. Early detection of different retinal-related diseases will dramatically reduce the risk of vision loss. Optical Coherence Tomography (OCT) is a relatively new imaging technique which is of great importance in the identification of ocular and especially retinal diseases. Thus, the efficient analysis of OCT images provides several advantages. In this thesis, we propose a series of image processing and machine learning techniques for the automated analysis of OCT images. The proposed methodology in chapter 2 localizes different retinal layers using a modified version of active contour models. In chapter 3, we propose a method which classifies OCT images based on different pathological conditions using novel methods, e.g., transfer learning and new texture detection techniques. The proposed methods along with the clinically meaningful extracted characteristics provide numbers of applications and benefits, e.g., saving a considerable amount of time and providing more-efficient and -accurate indices for the diagnosis and treatment of different ocular diseases to ophthalmologists and finally reducing the overall risk of vision loss

Photocatalytic degradation of antibiotic and hydrogen production using diatom-templated 3D WO3-x@mesoporous carbon nanohybrid under visible light irradiation

Synthesis of highly efficient 3D photocatalysts offers unique abilities for hydrogen production and chemical conversion to find a solution for energy shortage and environmental pollution issues. However, current strategies for production of ordered nanohybrid photocatalysts usually involve complex procedures and the use of expensive templates, which limit their practical applications. In this work, 3D WO3-x@mesoporous carbon photocatalyst was fabricated through one-pot evaporation-induced self-assembly (EISA) process using Cyclotella sp. as natural template. During heat-treatment, the precursor of carbon could partially reduce tungsten oxide under N-2 atmosphere leading to the embedding of WO3-x in conductive mesoporous carbon structure. The diatom templated WO3-x@mesoporous carbon (DTWO3-x@MC) nanohybrid exhibited high surface area (195.37 m(2) g(-1)) and narrowed band gap (2.67 eV). Integration of tungsten oxide with mesoporous carbon and formation of oxygen vacancies enhanced the absorption of visible light using DT-WO3-x@MC and limited the recombination of electron-hole pairs. 98.7% of cefazolin (CFZ) degradation efficiency and 85.5% of total organic carbon (TOC) removal efficiency were observed within 90 and 180 min under visible light irradiation, respectively. Scavenger quenching tests and electron spin resonance (ESR) analysis demonstrated that O-2(center dot-) played a main role in photocatalysis. CFZ degradation pathway was proposed via identification of conversion intermediates using GC-MS analysis. Photocatalytic hydrogen production rates of the pure WO3 and the DT-WO3-x@MC nanohybrid were determined as 746 and 1851 mmol g(-1) h(-1), respectively. This study presented a way to develop a high-performance and stable photocatalyst using diatom frustules as natural template which works under practical conditions for environmental remediation and energy production. (C) 2020 Elsevier Ltd. All rights reserved.Peer reviewe

Template-free hierarchical trimetallic oxide photocatalyst derived from organically modified ZnCuCo layered double hydroxide

High-performance photocatalysts have considerable potential to address energy and environmental issues. In this study, dodecylbenzenesulfonate (DBS) modified ZnCuCo layered double hydroxide (DBS-ZnCuCo LDH) microspheres were synthesized through the facile template-free hydrothermal method. Subsequently, ZnCuCo mixedmetal oxides (MMOs) with morphological features of the DBS modified LDH, enhanced surface area, increased light absorption and effective charge separation were prepared by the calcination of the as-synthesized LDH at 650 degrees C. Structural, morphological, and photoelectrochemical properties of ZnCuCo and DBS-ZnCuCo LDHs and the corresponding MMOs (ZnCuCo MMO1 and ZnCuCo MMO2) were investigated. SEM and TEM images revealed that DBS-ZnCuCo LDH and ZnCuCo MMO2 possess 3D flower-like hierarchical morphologies with interlaced petal-like nanosheets. Although ZnCuCo LDH was inactive for photocatalytic H-2 production under visible light irradiation, ZnCuCo MMO2 exhibited a high H2 production rate (3700 mu mol g(-1) h(-1)), benefiting from the synergy of the ZnO, CuO, and Co3O4. Furthermore, 95% sulfamethazine (SMZ) degradation was obtained after 60 min of photocatalysis, which is considerably higher than the degradation efficiency of ZnCuCo LDH (24%) and ZnCuCo MMO1 (58%). Based on the photoelectrochemical tests, Z-scheme and double charge transfer mechanisms were proposed to explain the enhanced photocatalytic H-2 production and degradation of SMZ. Scavenging tests revealed that O-2(center dot-) radicals were the main reactive species in the photodegradation of SMZ. A possible degradation pathway was proposed based on the detection of intermediate products.Peer reviewe

Synthesis of N-Doped Magnetic WO3–x@Mesoporous Carbon Using a Diatom Template and Plasma Modification : Visible-Light-Driven Photocatalytic Activities

Synthesis of three-dimensional photocatalysts offers great potential for chemical conversion and hydrogen generation as appropriate solutions for environmental protection and energy shortage challenges. In this study, the magnetic WO3–x@mesoporous carbon (M-WO3–x@MC) was synthesized through the evaporation-induced self-assembly method applying diatom frustules as a natural template. Then, plasma modification was used to prepare the N-doped M-WO3–x@MC (NM-WO3–x@MC) with enhanced photocatalytic activity and durable performance. The WO3–x was embedded in the conductive MC, which was also partially reduced by the carbon precursor within the heat-treatment procedure. The obtained M-WO3–x@MC was treated by the plasma under an N2 atmosphere for the production of the final photocatalyst containing both the N-doped WO3–x and MC. As a result, the NM-WO3–x@MC had larger surface area (208.4 m2 g–1), narrower band gap (2.3 eV), more visible light harvesting, and confined electron–hole pairs recombination. The H2 generation rates of net WO3 nanorods and NM-WO3–x@MC nanocomposite were estimated as 532 and 2765 μmol g–1 h–1, respectively. Additionally, more than 90% of antibiotics (cephalexin, cefazolin and cephradine) degradation and 76% of total organic carbon elimination were obtained after 120 and 240 min of photocatalytic process under visible light irradiation. Eventually, more than eight intermediates were detected for each antibiotic degradation using the gas chromatography–mass spectrometer method, and based on the obtained results, the possible degradation pathways were suggested.Peer reviewe

2-Approximation for Prize-Collecting Steiner Forest

Approximation algorithms for the prize-collecting Steiner forest problem (PCSF) have been a subject of research for over three decades, starting with the seminal works of Agrawal, Klein, and Ravi and Goemans and Williamson on Steiner forest and prize-collecting problems. In this paper, we propose and analyze a natural deterministic algorithm for PCSF that achieves a $2$-approximate solution in polynomial time. This represents a significant improvement compared to the previously best known algorithm with a $2.54$-approximation factor developed by Hajiaghayi and Jain in 2006. Furthermore, K{\"{o}}nemann, Olver, Pashkovich, Ravi, Swamy, and Vygen have established an integrality gap of at least $9/4$ for the natural LP relaxation for PCSF. However, we surpass this gap through the utilization of a combinatorial algorithm and a novel analysis technique. Since $2$ is the best known approximation guarantee for Steiner forest problem, which is a special case of PCSF, our result matches this factor and closes the gap between the Steiner forest problem and its generalized version, PCSF

Comparison between structural configurations designed by steel shear wall, moment resistant frame and X shape bracing systems

Nowadays, in order to increase construction of tall structures, the importance of choosing optimum systems, with a huge energy absorption capacity against wind and earthquake loads, has been widely considered. Since four decades ago, steel shear walls had been used as a stiff and high performance lateral system. This study is about the effect of concrete filled steel tubes (CFT) columns as vertical boundary elements of steel shear wall on seismic behavior of steel structures. Due to do this, three 10- storey steel structures, with similar plans and lateral load career systems of steel shear wall, coinciding X-bracing, and moderate steel frame were analyzed by means of non-linear, time-history method through SAP2000 software, and the results of roof displacement of them were compared with each other. Also after validating a two-storey, single-span frame sample with steel shear walls and CFT columns, 3 single-storey structures were analyzed by means of hysteresis and pushover, through ABAQUS software. The results of this study showed that a shear wall system presents suitable stiffness, resistance and ductility in comparison with other lateral bearing systems.Peer ReviewedPostprint (published version

Sonophotocatalytic degradation of sulfadiazine by integration of microfibrillated carboxymethyl cellulose with Zn-Cu-Mg mixed metal hydroxide/g-C3N4 composite

This research aimed to prepare a recoverable sonophotocatalyst, in which microfibrillated carboxymethyl cellulose (MFC) acted as the Zn-Cu-Mg-mixed metal hydroxide/graphitic carbon nitride (MMH/g-C3N4) carrier. The characteristics of bare and composite sonophotocatalysts were analyzed by the XRD, FT-IR, BET, DRS, PL and FE-SEM equipped with the EDX mapping. The performance of prepared composites (MMH/g-C3N4@MFC) with various weight ratios of the MMH/g-C3N4 was studied for the sonophotocatalytic degradation of sulfadiazine (SDZ) as the model emerging contaminant. 93% of SDZ was degraded using the most effective catalyst (MMH/gC(3)N(4)@MFC3) with 15% weight ratio of the MMH/g-C3N4 under the desired operating conditions including solution pH of 6.5, SDZ concentration of 0.15 mM and ultrasonic power of 300 W. The MMH addition to the gC(3)N(4) structure increased the separation of charge carriers generated via the visible light or ultrasound irradiations. Moreover, the MMH/g-C3N4 was dispersed uniformly on the MFC and consequently, more active sites were available to form reactive oxygen species (ROS), compared to powder form. Hydroxyl radicals ((OH)-O-center dot) were determined as the main ROS in the SDZ degradation by performing a series of scavenging experiments. Less than 10% decrease in the degradation efficiency of SDZ was observed during five subsequent experiments, which indicated the proper retention of the MMH/g-C3N4 particles in the MFC. The adequate mineralization of SDZ (83% decrease in chemical oxygen demand (COD)) was obtained after 200 min of treatment. Eventually, ten degradation intermediates were identified by the GC-MS analysis and a plausible degradation mechanism for the contaminant was proposed.Peer reviewe