Processing and Visualization of Protec-Seq Data for the Generation of Calibrated, Genome-Wide Double Double-Strand Break (dDSB) Maps.

This chapter describes the computational pipeline for the processing and visualization of Protec-Seq data, a method for purification and genome-wide mapping of double-stranded DNA protected by a specific protein at both ends. In the published case, the protein of choice was Saccharomyces cerevisiae Spo11, a conserved topoisomerase-like enzyme that makes meiotic double-strand breaks (DSBs) to initiate homologous recombination, ensuring proper segregation of homologous chromosomes and fertility. The isolated DNA molecules were thus termed double DSB (dDSB) fragments and were found to represent 34 to several hundred base-pair long segments that are generated by Spo11 and are enriched at DSB hotspots, which are sites of topological stress. In order to allow quantitative comparisons between dDSB profiles across experiments, we implemented calibrated chromatin immunoprecipitation sequencing (ChIP-Seq) using the meiosis-competent yeast species Saccharomyces kudriavzevii as calibration strain. Here, we provide a detailed description of the computational methods for processing, analyzing, and visualizing Protec-Seq data, comprising the download of the raw data, the calibrated genome-wide alignments, and the scripted creation of either arc plots or Hi-C-style heatmaps for the illustration of chromosomal regions of interest. The workflow is based on Linux shell scripts (including wrappers for publicly available, open-source software) as well as R scripts and is highly customizable through its modular structure.

The predictive value of the ARC-HBR criteria for in-hospital bleeding risk following percutaneous coronary intervention in patients with acute coronary syndrome.

Background: The Academic Research Consortium for High Bleeding Risk (ARC-HBR) criteria were proposed for predicting bleeding risk in patients undergoing percutaneous coronary intervention (PCI). However, there is a lack of research evaluating the risk of in-hospital bleeding following PCI for acute coronary syndrome (ACS) utilizing the ARC-HBR criteria. Methods and results: This study involved 1013 ACS patients who underwent PCI and dual antiplatelet therapy. There were 63 cases of in-hospital bleeding events (6.22 %). According to the ARC-HBR criteria, patients classified as HBR had a significantly greater bleeding rate than non-HBR patients (15.81 % vs. 1.99 %, p < 0.001). As the CRUSADE score category increased, the risk of bleeding also increased. The area under the receiver operating characteristic curve (AUC) of the ARC-HBR criteria was significantly greater than that of the CRUSADE score for bleeding (0.751 vs. 0.696, p < 0.0001). Subgroup analysis revealed that the ARC-HBR criteria exhibited better predictive ability for ST-segment elevation myocardial infarction (STEMI, AUC 0.767 vs. 0.694, p = 0.020) but comparable predictive ability in patients with unstable angina (AUC 0.756 vs. 0.644, p = 0.213), non-ST-segment elevation myocardial infarction (AUC 0.713 vs. 0.683, p = 0.644), and non-ST-segment elevation ACS (AUC 0.739 vs. 0.687, p = 0.330). Conclusion: Compared with the CRUSADE score, the ARC-HBR criteria demonstrate superior predictive ability for in-hospital bleeding events during PCI in ACS patients. Routine assessment of the ARC-HBR score might be helpful for identifying high-risk individuals in this specific population.

Dosimetric consequences of adapting the craniocaudal isocenter distance to daily patient position in craniospinal irradiation using volumetric modulated arc therapy.

PURPOSE: In craniospinal irradiation, two or three isocenter groups along the craniocaudal axis are required to cover the long treatment target. Adapting the isocenter distance according to daily deviations in patient position is challenging because dosimetric hot or cold spots may occur in the field junction. The aim of this study was to quantify the effect of adapting the isocenter distance to patient position on the dose distribution of the field overlap region in craniospinal irradiation using partial-arc volumetric modulated arc therapy. METHODS: The magnitude of isocenter distance deviations in craniocaudal direction was quantified by registering the setup images of 204 fractions of 12 patients to the planning images. The dosimetric effect of these deviations was determined by shifting the isocenters of the original treatment plan and calculating the resulting dose distribution. RESULTS: On fraction-level, deviations larger than 3 mm caused more than 5 percentage point changes in the doses covering 2% (D2%) and 98% (D98%) of the junction volume in several patients. On treatment course-level, the changes in D2% and D98% of the junction volume were less than 5 percentage points in all cases except for one patient. CONCLUSIONS: Craniocaudal isocenter distance adaptation can be conducted provided that the mean isocenter distance deviation over the treatment course is within 3 mm.

Proton ARC based LATTICE radiation therapy: feasibility study, energy layer optimization and LET optimization.

Objective.LATTICE, a spatially fractionated radiation therapy (SFRT) modality, is a 3D generalization of GRID and delivers highly modulated peak-valley spatial dose distribution to tumor targets, characterized by peak-to-valley dose ratio (PVDR). Proton LATTICE is highly desirable, because of the potential synergy of the benefit from protons compared to photons, and the benefit from LATTICE compared to GRID. Proton LATTICE using standard proton RT via intensity modulated proton therapy (IMPT) (with a few beam angles) can be problematic with poor target dose coverage and high dose spill to organs-at-risk (OAR). This work will develop novel proton LATTICE method via proton ARC (with many beam angles) to overcome these challenges in target coverage and OAR sparing, with optimized delivery efficiency via energy layer optimization and optimized biological dose distribution via linear energy transfer (LET) optimization, to enable the clinical use of proton LATTICE.Approach.ARC based proton LATTICE is formulated and solved with energy layer optimization, during which plan quality and delivery efficiency are jointly optimized. In particular, the number of energy jumps (NEJ) is explicitly modelled and minimized during plan optimization for improving delivery efficiency, while target dose conformality and OAR dose objectives are optimized. The plan deliverability is ensured by considering the minimum-monitor-unit (MMU) constraint, and the plan robustness is accounted for using robust optimization. The biological dose is optimized via LET optimization. The optimization solution algorithm utilizes iterative convex relaxation method to handle the dose-volume constraint and the MMU constraint, with spot-weight optimization subproblems solved by proximal descent method.Main results.ARC based proton LATTCE substantially improved plan quality from IMPT based proton LATTICE, such as (1) improved conformity index (CI) from 0.47 to 0.81 for the valley target dose and from 0.62 to 0.97 for the peak target dose, (2) reduced esophagus dose from 0.68 Gy to 0.44 Gy (a 12% reduction with respect to 2 Gy valley prescription dose) and (3) improved PVDR from 4.15 to 4.28 in the lung case. Moreover, energy layer optimization improved plan delivery efficiency for ARC based proton LATTICE, such as (1) reduced NEJ from 71 to 56 and (2) reduction of energy layer switching time by 65% and plan delivery time by 52% in the lung case. The biological target and OAR dose distributions were further enhanced via LET optimization. On the other hand, proton ARC LATTCE also substantially improved plan quality from VMAT LATTICE, such as (1) improved CI from 0.45 to 0.81 for the valley target dose and from 0.63 to 0.97 for the peak target dose, (2) reduced esophagus dose from 0.59 Gy to 0.38 Gy (a 10.5% reduction with respect to 2 Gy valley prescription dose) and (3) improved PVDR from 3.88 to 4.28 in the lung case.Significance.The feasibility of high-plan-quality proton LATTICE is demonstrated via proton ARC with substantially improved target dose coverage and OAR sparing compared to IMPT, while the plan delivery efficiency for ARC based proton LATTICE can be optimized using energy layer optimization.

Study of Residual Stress Using Phased Array Ultrasonics in Ti-6AL-4V Wire-Arc Additively Manufactured Components.

This paper presents a study on residual stress measurement in wire-arc additively manufactured (WAAM) titanium samples using the non-destructive method of phased array ultrasonics. The contour method (CM) was used for the verification of the phased array ultrasonic results. This allowed for a comparison of measurement methods to understand the effects on the distribution of residual stress (RS) within Ti-6Al-4V samples and the effectiveness of measurement of residual stress using phased array ultrasonics. From the results of the experiments, the phased array ultrasonic data were found to be in good agreement with the CM results and displayed similar residual stress distributions in the samples. The results of the individual elements of the phased array were also compared and an improvement in accuracy was found. From per-element results, anomalies were found and could be mitigated with the ability to average the results by using phased array ultrasonics. Therefore, based on these results, there is a strong case for the benefits of using phased array ultrasonics as a method of residual stress measurement for WAAM Ti-6Al-4V components over other existing residual stress measurement techniques.

Emulating the Delivery of Sawtooth Proton Arc Therapy Plans on a Cyclotron-Based Proton Beam Therapy System.

Purpose: To evaluate and compare the deliverability of 'sawtooth' proton arc therapy (PAT) plans relative to static intensity modulated proton therapy (IMPT) at a cyclotron-based clinical facility. Methods: The delivery of single and dual arc Sawtooth PAT plans for an abdominal CT phantom and multiple clinical cases of brain, head and neck (H&N) and base of skull (BoS) targets was emulated under the step-and-shoot and continuous PAT delivery regimes and compared to that of a corresponding static IMPT plan. Results: Continuous PAT delivery increased the time associated with beam delivery and gantry movement in single/dual PAT plans by 4.86/7.34 min (brain), 7.51/12.40 min (BoS) and 6.59/10.57 min (H&N) on average relative to static IMPT. Step-and-shoot PAT increased this delivery time further by 4.79 min on average as the delivery was limited by gantry motion. Conclusions: The emulator can approximately model clinical sawtooth PAT delivery but requires experimental validation. No clear benefit was observed regarding beam-on time for sawtooth PAT relative to static IMPT.

Effect of N2/Ar Ratio on Wear Behavior of Multi-Element Nitride Coatings on AISI H13 Tool Steel.

In this study, multi-element nitride coatings composed of (Ti, Cr, Cu, Al, Si)N were synthesized on H13 tool steel using cathodic arc deposition (CAD) technology. The N2/Ar flow ratio varied from 0 to 2 as the experimental parameter, and two targets, Ti-Cr-Cu and Al-Si alloys, were utilized simultaneously. The impact of the gas flow ratio on the coatings' abrasion properties was investigated, focusing on aspects, such as chemical composition, adhesion, hardness, and wear behavior. The experimental findings indicate that the coated specimens with a nitrogen reaction exhibit superior hardness and abrasion resistance compared to those without nitrogen use. While the surface roughness of the specimens tends to increase slightly with a higher N2/Ar ratio, the coating demonstrates improved hardness, adhesion, and abrasion resistance performance. In summary, the wear-resistant characteristics of H13 tool steel can be significantly enhanced when applying a CAD-(Ti, Cr, Cu, Al, Si)N film with a flow ratio of N2/Ar = 2.

Unsupervised machine learning model for detecting anomalous volumetric modulated arc therapy plans for lung cancer patients.

Purpose: Volumetric modulated arc therapy (VMAT) is a new treatment modality in modern radiotherapy. To ensure the quality of the radiotherapy plan, a physics plan review is routinely conducted by senior clinicians; however, this process is less efficient and less accurate. In this study, a multi-task AutoEncoder (AE) is proposed to automate anomaly detection of VMAT plans for lung cancer patients. Methods: The feature maps are first extracted from a VMAT plan. Then, a multi-task AE is trained based on the input of a feature map, and its output is the two targets (beam aperture and prescribed dose). Based on the distribution of reconstruction errors on the training set, a detection threshold value is obtained. For a testing sample, its reconstruction error is calculated using the AE model and compared with the threshold value to determine its classes (anomaly or regular). The proposed multi-task AE model is compared to the other existing AE models, including Vanilla AE, Contractive AE, and Variational AE. The area under the receiver operating characteristic curve (AUC) and the other statistics are used to evaluate the performance of these models. Results: Among the four tested AE models, the proposed multi-task AE model achieves the highest values in AUC (0.964), accuracy (0.821), precision (0.471), and F1 score (0.632), and the lowest value in FPR (0.206). Conclusion: The proposed multi-task AE model using two-dimensional (2D) feature maps can effectively detect anomalies in radiotherapy plans for lung cancer patients. Compared to the other existing AE models, the multi-task AE is more accurate and efficient. The proposed model provides a feasible way to carry out automated anomaly detection of VMAT plans in radiotherapy.

Sectored single-energy volumetric-modulated proton arc therapy (VPAT): A preliminary multi-disease-site concept study.

PURPOSE: To explore the feasibility of a novel intensity-modulated proton arc technique that uses a single-energy beam from the cyclotron. The beam energy is externally modulated at each gantry angle by a tertiary energy modulator (EM). We hypothesize that irradiating in an arc without requiring an energy change from the cyclotron will achieve a faster delivery (main advantage of our technique) while keeping clinically desirable dosimetric results. METHODS: In a retrospective cohort of four patients with female pelvis, prostate, lung, and brain cancers, we investigated our volumetric-modulated proton arc therapy (VPAT) technique. Arcs were simulated by sectors of 1°-spaced static beams. Keeping the energy requested from the cyclotron the same for each entire arc was supported by a predesigned EM placed in front of the nozzle. As a feasibility measure, EM thicknesses were calculated. Delivery times and doses to targets and organs at risk (OARs) were compared to those of the clinical plans. RESULTS: VPAT plans were comparable to their clinical counterparts in achieving target dose conformity, being robust to uncertainties, and meeting clinical dose-volume constraints. Cyclotron energies for the four cases were within 159-220 MeV, and energy modulation range was 69-100 MeV, equivalent to 13-19 cm of water-equivalent thickness (WET). Plan delivery times were reduced from > 5 min in our clinical practice to < 3.5 min in VPAT. CONCLUSION: For the evaluated plans, the novel VPAT approach achieved shorter delivery times without sacrificing robustness, OAR sparing or target coverage. VPAT's EMs had WETs implementable in a clinical setup.

Tensile, Fatigue Properties and Their Anisotropies of Al-Mg Alloy Fabricated by Wire-Arc Additive Manufacturing.

The microstructure, mechanical properties (tensile, fatigue, etc.) and the anisotropies of the Al-Mg alloy fabricated by wire arc additive manufacturing are studied in this work. The results show that the microstructure of the deposited alloy is composed of coarse columnar grains in the inner-layer region and fine equiaxed grains in the interlayer region. The tensile and fatigue properties exhibit strong anisotropies. The ultimate tensile strength (258 MPa), yield strength (140 MPa), elongation (21.3%), and fatigue life (2.56 × 105) of the sample along travel direction (0° direction) are the best, whereas those of the sample along the deposited direction (90° direction) are the lowest and those of the sample along 45° direction are the medium. It is found that the lowest strength and elongation of the sample in the deposited direction can be attributed to the large weak bonding areas between the deposition layers, whereas the lowest fatigue property is associated with the fatigue crack propagation along the grain boundaries of the columnar grains.

Effects of Pulse Interval on Forming Process in Wire Arc Metal Additive Manufacturing Using Pulsed Arc Plasma.

To overcome the material processing challenges induced by high levels of heat input in wire arc additive manufacturing (WAAM), an innovative WAAM method using pulsed arc plasma (PAP-WAAM), was developed by the authors in the previous study. In this method, the PAP generated by the pulsed voltage was used as the heat source. The pulse interval can be defined as the time interval between adjacent pulse voltages, which determines the ignition time and frequency of the arc plasma, thus influencing the forming process. However, the effect of pulse interval on the forming process has not yet been revealed. Here, the effects of pulse interval on forming process during the PAP-WAAM of Ti6Al4V, including thermal behavior, arc plasma characteristics, and metal transfer process, were investigated by experiments and simulation. The results exhibited that the interpass temperature and maximum peak temperature decrease with increasing pulse interval at the same arc plasma power, indicating an alleviation of heat accumulation along the building direction. As the pulse interval increased, the ignition mode of the arc plasma changed from ignition between the tungsten electrode and the previously deposited layer to ignition between the tungsten electrode and filler wire, which increased the proportion of discharge energy allocated to the filler wire, thus reducing the overall heat input required for material deposition. When the pulse interval was 300 and 400 ms, only the uninterrupted bridging transfer mode was observed during the deposition process. The uninterrupted bridging transfer is considered to contribute to forming a smooth and consistent layer appearance. In addition, longer pulse intervals resulted in less surface oxidation, narrower wall thickness, and better macrostructure, attributed to reduced heat input and improved effective heat dissipation. This research reveals the effect of pulse interval on forming process during PAP-WAAM, which benefits the fabrication of desirable metal parts.

RETINAL BURNS IN PHOTIC RETINOPATHY: THREE CASE REPORTS.

Photic retinopathy (PR) is due to retinal phototoxicity, especially affecting the macula, resulting from exposure to sun, welding devices and lasers. It leads to oxidative damage to the retinal pigment epithelium (RPE) and the surrounding photoreceptors. Early recognition of this visual threatening condition, follow-up lesion evolution, and prevention of prolonged ocular exposure to lights is warranted. We herein report the three principal types of retinal burns due to solar retinopathy, laser pointer-induced maculopathy and arc welding maculopathy.

La rétinopathie photique (RP) est secondaire à une phototoxicité rétinienne, affectant particulièrement la macula, résultant de l'exposition au soleil, aux appareils de soudure et aux lasers. Elle entraîne un dommage oxydatif de l'épithélium pigmentaire de la rétine (EPR) et des photorécepteurs. Il s'avère primordial de reconnaître précocement cette affection menaçant la vision, de suivre l'évolution des lésions et de prévenir une exposition oculaire prolongée aux lumières. Nous rapportons ici les trois principaux types de brûlures rétiniennes, dues à la rétinopathie solaire, à la maculopathie induite par un pointeur laser et à la maculopathie de soudure à l'arc.

Open surgical repair of an isolated aneurysm of the arc of Riolan with celiac artery occlusion and severe superior mesenteric artery stenosis.

The arc of Riolan (AoR), a marginal vessel in the left colon, interconnects the superior and inferior mesenteric arteries. A 65-year-old woman presented with an incidental aneurysmal lesion in the left upper abdomen found on ultrasound. Computed tomography revealed a 27-mm saccular aneurysm in the AoR with occlusion of the celiac artery and severe stenosis of the superior mesenteric artery. Angiography showed that the inferior mesenteric artery provided blood to the perfusion areas of the superior mesenteric artery, celiac artery, and left colon via the AoR. We performed open surgical repair of the aneurysm and reconstruction of the inferior mesenteric artery.

Detection and analysis of complex structural variation in human genomes across populations and in brains of donors with psychiatric disorders.

Complex structural variations (cxSVs) are often overlooked in genome analyses due to detection challenges. We developed ARC-SV, a probabilistic and machine-learning-based method that enables accurate detection and reconstruction of cxSVs from standard datasets. By applying ARC-SV across 4,262 genomes representing all continental populations, we identified cxSVs as a significant source of natural human genetic variation. Rare cxSVs have a propensity to occur in neural genes and loci that underwent rapid human-specific evolution, including those regulating corticogenesis. By performing single-nucleus multiomics in postmortem brains, we discovered cxSVs associated with differential gene expression and chromatin accessibility across various brain regions and cell types. Additionally, cxSVs detected in brains of psychiatric cases are enriched for linkage with psychiatric GWAS risk alleles detected in the same brains. Furthermore, our analysis revealed significantly decreased brain-region- and cell-type-specific expression of cxSV genes, specifically for psychiatric cases, implicating cxSVs in the molecular etiology of major neuropsychiatric disorders.

A Nanobody-Based Proximity Ligation Assay Detects Constitutive and Stimulus-Regulated Native Arc/Arg3.1 Oligomers in Hippocampal Neuronal Dendrites.

Activity-regulated cytoskeleton-associated protein (Arc), the product of an immediate early gene, plays critical roles in synaptic plasticity and memory. Evidence suggests that Arc function is determined by its oligomeric state; however, methods for localization of native Arc oligomers are lacking. Here, we developed a nanobody-based proximity ligation assay (PLA) for detection, localization, and quantification of Arc-Arc complexes in primary rat hippocampal neuronal cultures. We used nanobodies with single, structurally defined epitopes in the bilobar Arc capsid domain. Nanobody H11 binds inside the N-lobe ligand pocket, while nanobody C11 binds to the C-lobe surface. For each nanobody, ALFA- and FLAG-epitope tags created a platform for antibody binding and PLA. Surprisingly, PLA puncta in neuronal dendrites revealed widespread constitutive Arc-Arc complexes. Treatment of cultures with tetrodotoxin or cycloheximide had no effect, suggesting stable complexes that are independent of recent neuronal activity and protein synthesis. To assess detection of oligomers, cultures were exposed to a cell-penetrating peptide inhibitor of the Arc oligomerization motif (OligoOFF). Arc-Arc complexes detected by H11 PLA were inhibited by OligoOff but not by control peptide. Notably, Arc complexes detected by C11 were unaffected by OligoOFF. Furthermore, we evaluated Arc complex formation after chemical stimuli that increase Arc synthesis. Brain-derived neurotrophic factor increased Arc-Arc signal detected by C11, but not H11. Conversely, dihydroxyphenylglycine (DHPG) treatment selectively enhanced H11 PLA signals. In sum, nanobody-based PLA reveals constitutive and stimulus-regulated Arc oligomers in hippocampal neuronal dendrites. A model is proposed based on detection of Arc dimer by C11 and higher-order oligomer by H11 nanobody.

Treating a Refractory Locally Advanced Carcinoma of the Cervix With Cone-Beam Computed Tomography-Based Adaptive External Beam Radiotherapy: A Case Report.

Adaptive radiotherapy (ART) refers to methods that allow a radiation therapy plan to be adjusted based on images obtained during the treatment. Using cutting-edge imaging methods such as computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET), ART can adjust the treatment plan in response to observed changes in anatomy and even biology while the patient is receiving treatment. The backbone of ART is intensity-modulated RT (IMRT), which permits better sparing of normal critical organs while still delivering a uniform dose to target tumor volume. Volumetric modulated arc therapy (VMAT) is a more rapid form of IMRT with more conformity, which helps in treating patients in a shorter time. Different types of ART include individualized margins using an internal target volume (ITV) and offline and online methods. ITV uses the margin to appropriately cover the clinical target volume (CTV) based on matching CT scans to different extents of the radiological anatomy of the selected area. Offline adaptive strategies include scheduled replanning throughout the external beam radiotherapy (EBRT) course, depending on intra-fraction or inter-fraction changes. The online ART (oART) strategy takes into account changes in tumor volume and the daily anatomical variations of target volumes and organs at risk structures (OARS). As such, PTV margins have the potential to be reduced. Commercially available oART systems are predominantly MRI-guided, but more recent advances have seen the creation of a cone-beam CT (CBCT)-guided oART system. In this case of FIGO (International Federation of Gynaecology and Obstetrics) stage IIB squamous cell carcinoma of the uterine cervix, we used an offline ART approach to complete the initial part of the treatment, which included concurrent chemoradiation therapy with 50 Gy/25 Fr and weekly cisplatin for five weeks. However, in the final fraction of on-couch kilovoltage CBCT (kvCBCT), it appears that the tumor only partially responded, demonstrating its refractory nature to treatment. The patient then underwent a repeat planning contrast-enhanced CT (CECT) scan, which was fused with the initial planning CECT scan. It revealed that the tumor responded poorly, with only a slight decrease in size. With the OARS toxicity limit in mind, the patient was scheduled for an adapted volumetric modulated arc therapy (VMAT) boost of 8 Gy/4 Fr as a second-phase plan for the tumor. Subsequently, the patient was taken up for intra-cavitary brachytherapy (ICBT) after a one-week gap. She received brachytherapy with 9 Gy/session for two sessions as per institutional protocol on a weekly basis. On subsequent follow-up, the patient underwent a complete response clinico-radiologically, even after two years of follow-up. This case report shows the importance of adaptive radiotherapy in treating tumors with a high therapeutic ratio and less toxicity to OARS despite employing the less frequently used EBRT boost along with ICBT brachytherapy.

Research on Low-Voltage Arc Fault Based on CNN-Transformer Parallel Neural Network with Threshold-Moving Optimization.

Low-voltage arc fault detection can effectively prevent fires, electric shocks, and other accidents, reducing potential risks to human life and property. The research on arc fault circuit interrupters (AFCIs) is of great significance for both safety in production scenarios and daily living disaster prevention. Considering the diverse characteristics of loads between the normal operational state and the arc fault condition, a parallel neural network structure is proposed for arc fault recognition, which is based on a convolutional neural network (CNN) and a Transformer. The network uses convolutional layers and Transformer encoders to process the low-frequency current and high-frequency components, respectively. Then, it uses Softmax classification to perform supervised learning on the concatenated features. The method combines the advantages of both networks and effectively reduces the required depth and computational complexity. The experimental results show that the accuracy of this method can reach 99.74%, and with the threshold-moving method, the erroneous judgment rate can be lower. These results indicate that the parallel neural network can definitely detect arc faults and also improve recognition efficiency due to its lean structure.

Applications of H2-Enriched syngas and slag products from plastic wastes via novel plasma dual-stage-arc pyrolysis.

Sustainable plastic waste management in the prevailing 'new-normal' post-pandemic scenario calls for calorific waste plastic up-cycling into high-end product recovery pathways. The present work employed a novel dual-stage arc plasma pyrolysis reactor to recover syngas and slag products from mixed plastics and Low-Density Polyethylene and Polyethylene Terephthalate (LDPE-PET) plastic waste feeds. Syngas product yield decreased while the solid slag yield increased with rising arc current, attaining 75% and 25% for mixed plastic waste feed and 59% and 41% for LDPE-PET wastes, respectively, at 200A arc current. The resultant syngas composition showed 83% and 77% H2 while 1.7% and 2.7% CO for mixed plastic waste-feed and LDPE-PET wastes, respectively, with no significant presence of CO2. Slag characterization studies revealed the presence of scattered pores on the slag surface, graphitic nanostructures due to scraped carbon depositions from electrode tips and the absence of aromatic groups due to complete conversion. High carbon content was observed in the slag due to the dissociation of lighter hydrocarbon and carbon dioxide on dual-arc exposure in two stages, underscoring the higher efficiency. For holistic integrated circular onsite 'plastic waste-to-resource' recovery-cum-application, electricity was generated from the resultant syngas and the slag was used for the manufacture of tiles in the community platform. Techno-economic evaluation of an up-scaled plasma pyrolysis facility shows the power recovery of 3.5 kWh/kg of waste plastic, with a net annual profit of $2800 and a payback period of 1.7 years. The findings of the present work suggest that the proposed integrated dual-arc plasma pyrolysis based plastic waste-to-resource recovery in circular-economy model has a viable outcome.

A Net Shape Profile Extraction Approach for Exploring the Forming Appearance of Inclined Thick-Walled Structures by Wire Arc Additive Manufacturing.

Wire arc additive manufacturing (WAAM) offers a viable solution for fabricating large-scale metallic parts, which contain various forms of inclined thick-walled structure. Due to the variety of heat dissipation conditions at different positions, the inclined thick-walled structure is a major challenge in fabrication that may produce collapses and defects. However, there is a lack of effective sensing method for acquiring the forming appearance of individual beads in the structure. This paper proposes a novel approach for extracting individual bead profiles during the WAAM process. The approach utilizes a structured-laser sensor to capture the morphology of the surface before and after deposition, thereby enabling an accurate acquisition of the bead profile by integrating the laser stripes. Utilizing the proposed approach, the research investigated the forming mechanism of beads in inclined thick-walled components that were fabricated by various deposition parameters. The width of the overlapping area at the overhanging feature decreased as the layer number increased, while the height of the same area increased. The height of the overlapping area in each layer increased with an increase in deposition current and decreased when the deposition speed was increased. These phenomena suggest that the heat input is a major factor that influences the formation of the overhanging feature. Both the deposition current and deposition velocity influence heat input, and thereby have an effect in enhancing the geometrical accuracy of an overhanging feature. The experimental results indicate that the proposed approach facilitates morphology change investigation, providing a sufficient reference for optimizing deposition parameters.

Replacing manual planning with automatic iterative planning for locally advanced rectal cancer VMAT treatment.

PURPOSE: To develop and implement a fully automatic iterative planning (AIP) system in the clinical practice, generating volumetric-modulated arc therapy plans combined with simultaneous integrated boost technique VMAT (SIB-VMAT) for locally advanced rectal cancer (LARC) patients. METHOD: The designed AIP system aimed to automate the entire planning process through a web-based service, including auxiliary structure generation, plan creation, field configuration, plan optimization, dose calculation, and plan assessment. The system was implemented based on the Eclipse scripting application programming interface and an efficient iterative optimization algorithm was proposed to reduce the required iterations in the optimization process. To verify the performance of the implemented AIP system, we retrospectively selected a total of 106 patients and performed dosimetric comparisons between the automatic plans (APs) and the manual plans (MPs), in terms of dose-volume histogram (DVH) metrics, homogeneity index (HI), and conformity index (CI) for different volumes of interest. RESULT: The AIP system has successfully created 106 APs within clinically acceptable timeframes. The average planning time per case was 36.8 ± 6.5 min, with an average iteration number of 6.8 (±1.1) in plan optimization. Compared to MPs, APs exhibited better performance in the planning target volume conformity and hotspot control ( p < 0.001 $p < 0.001$ ). The organs at risk (OARs) sparing was significantly improved in APs, with mean dose reductions in the femoral heads, the bone marrow, and the SmallBowel-Avoid of 0.53 Gy, 1.18 Gy, and 1.00 Gy, respectively ( p < 0.001 $p < 0.001$ ). Slight improvement was also observed in the urinary bladder V 40 Gy ${{V}_{40{\mathrm{\ Gy}}}}$ and the small bowel D 2 cc ( p < 0.001 ) ${{D}_{2{\mathrm{\ cc}}}}\ (p < 0.001)$ . Additionally, quality variation between plans from different planners was observed in DVH metrics while the APs represented better plan quality consistency. CONCLUSION: An AIP system has been implemented and integrated into the clinical treatment planning workflow. The AIP-generated SIB-VMAT plans for LARC have demonstrated superior plan quality and consistency compared with the manual counterparts. In the meantime, the planning time has been reduced by the AIP approach. Based on the reported results, the implemented AIP framework has been proven to improve plan quality and planning efficiency, liberating planners from the laborious parameter-tuning in the optimization phase.