Surface Scanning Research Articles

Shape Analysis of Prosthetic Socket Rectification Procedure for Transtibial Amputees

Achieving a comfortable socket residual limb interface is crucial for effective prosthetic rehabilitation, depending on the precise characterisation and fluctuations in the shape and volume of residual limbs. Clinicians rely on subjective and iterative methods for shaping sockets, often involving a trial-and-error approach. This study introduces a framework for measuring, analysing, and comparing residual limb shape and volume using scanned data to facilitate more informed clinical decision-making. Surface scans of 44 transtibial residual limb casts of various sizes and lengths were examined. All scans were spatially aligned to a mid-patella and subjected to analysis using a shape analysis toolbox. Geometric measurements were extracted, with particular attention to significant rectified regions during the cast rectification process. Following PTB guidelines, our analysis revealed substantial alterations, primarily in the mid-patella region, followed by the patellar tendon area. Notably, there was a significant volume change of 6.02% in the region spanning from mid-patella to 25% of the cast length. Beyond this point, linear cast modifications were observed for most amputees up to 60% of the cast length, followed by individual-specific deviations beyond this region. Regardless of residual limb size and length, the modifications applied to positive casts suggested categorising patients into five major groups. This study employs the AmpScan shape analysis tool, to comprehend the cast rectification process used for capturing and assessing the extent of rectification on patients’ residual limb casts. The clinical implications of our research are threefold: (a) the comparison data can serve as training resources for junior prosthetists; (b) this will aid prosthetists in identifying specific regions for rectification and assessing socket fit; (c) it will help in determining optimal timing for prosthetic fitting or replacement.

Generative deep learning furthers the understanding of local distributions of fat and muscle on body shape and health using 3D surface scans

BackgroundBody shape, an intuitive health indicator, is deterministically driven by body composition. We developed and validated a deep learning model that generates accurate dual-energy X-ray absorptiometry (DXA) scans from three-dimensional optical body scans (3DO), enabling compositional analysis of the whole body and specified subregions. Previous works on generative medical imaging models lack quantitative validation and only report quality metrics.MethodsOur model was self-supervised pretrained on two large clinical DXA datasets and fine-tuned using the Shape Up! Adults study dataset. Model-predicted scans from a holdout test set were evaluated using clinical commercial DXA software for compositional accuracy.ResultsPredicted DXA scans achieve R2 of 0.73, 0.89, and 0.99 and RMSEs of 5.32, 6.56, and 4.15 kg for total fat mass (FM), fat-free mass (FFM), and total mass, respectively. Custom subregion analysis results in R2s of 0.70–0.89 for left and right thigh composition. We demonstrate the ability of models to produce quantitatively accurate visualizations of soft tissue and bone, confirming a strong relationship between body shape and composition.ConclusionsThis work highlights the potential of generative models in medical imaging and reinforces the importance of quantitative validation for assessing their clinical utility.

Novel Technique of Interproximal Enamel Reduction Based on Computer-Aided Navigation Technique-An In Vitro Study.

The aim of this study was to analyze and compare the accuracy of a novel interproximal enamel reduction (IPR) technique based on a computer-aided static navigation technique with respect to a conventional free-hand-based technique for interproximal enamel reduction. Twenty anatomical-based experimental cast models of polyurethane were randomly distributed into the following IPR techniques: IPR technique based on computer-aided static navigation technique (n = 10) (GI) for Group A and conventional free-hand-based technique for the IPR (n = 10) (FHT) for Group B. The anatomical-based experimental cast models of polyurethane randomly assigned to the GI study group were submitted for a preoperative 3D intraoral surface scan; then, datasets were uploaded into 3D implant-planning software to design virtual templates for the interproximal enamel reduction technique. Afterward, the anatomical-based experimental cast models of polyurethane of both GI and FHT study groups were subjected to a postoperative digital impression by a 3D intraoral surface scan to compare the accuracy of the interproximal enamel reduction techniques at the buccal (mm), lingual/palatal (mm), and angular (◦) levels using the Student t-test. Statistically significant differences between the interproximal enamel reduction technique based on the computer-aided static navigation technique and the conventional free-hand-based technique for the interproximal enamel reduction at the buccal (p = 0.0008) and lingual/palatal (p < 0.0001) levels; however, no statistically significant differences were shown at the angular level (p = 0.1042). The interproximal enamel reduction technique based on computer-aided static navigation technique was more accurate than the conventional free-hand-based technique for interproximal enamel reduction.

Fossilized autogenic responses of grain‐size transition to sediment supply and water discharge: Alluvial fan experiments

ABSTRACTAutogenic feedbacks can produce large‐scale, organized stratigraphic patterns in alluvial fans, but autogenic depositional signatures of specific upstream boundary conditions remain challenging to interpret. Here, a combination of theory, experiment and field application is used to explore how autogenic lithofacies changes can be interpreted as stratigraphic indicators of upstream boundary conditions. Six experiments were conducted to test the effects of sediment supply and water discharge rates on autogenic advance and retreat of the lithofacies boundary (grain‐size transition) in an alluvial fan with two dominant grain sizes. Migration of the grain‐size transition caused a short‐term zigzag pattern in the grain‐size transition position in the dip‐directional deposit section. For each experiment, time‐lapse images and laser topographic scans of the fan surface and stratigraphic cross‐sections of the final deposits were used to quantify characteristic timescales of autogenic processes. Timescales for fan‐margin migration, surface wet‐fraction change and grain‐size transition migration generally shorten as sediment supply rate increases and water discharge rate decreases. Increasing the sediment supply rate shortens the duration of the fluvial sediment storage and release cycle, producing higher frequency zigzags in the grain‐size transition trajectory. Increasing the water discharge tends to widen channels and lengthens the duration of the fluvial sediment storage and release cycle, constructing lower frequency zigzags in the grain‐size transition trajectory. Increasing the water discharge also enables more sediment to transport further downstream during release events, leading to higher magnitude zigzags in the grain‐size transition trajectory. These relationships between upstream boundary conditions and the grain‐size transition trajectory demonstrate how autogenic stratigraphic signals could be used as a tool to infer relative changes in boundary conditions.

Assessment of Residual Stresses in Laser Powder Bed Fusion Manufactured IN 625.

Residual stresses pose significant challenges in the powder bed fusion of metals using a laser (PBF-LB/M), impacting both the dimensional accuracy and mechanical properties. This study quantitatively analyzes deformation and residual stresses in additively manufactured Inconel 625. Investigating both as-built and stress-relieved states with varied scanning strategies (90°, 67°, strip, and 90° chessboard) in PBF-LB/M/IN625, distortion is evaluated using the bridge curvature method. Quantitative measurements are obtained through 3D laser surface scanning on pairs of bridge specimens-one measured before and after detachment from the build plate, and the other undergoing stress-relieving heat treatment at 870 °C for 1 h. The findings reveal that, among as-built specimens, the 90° and 90° strip strategies induce the least distortion, followed by the 67° and chessboard 90° strategies. Furthermore, stress-relief treatment significantly reduces residual stress levels. After post-treatment, the deformation in X-axis samples with 90° and 90° strip strategies decreases by 39% and 42%. In contrast, the samples with the 67° and 90° checkerboard strategies exhibit more pronounced reductions of 44% and 63%, respectively. These quantitative results contribute useful insights for optimizing PBF-LB/M/IN625 processes in additive manufacturing.

Punctuated evolution of bill morphology in the largest family of songbirds (Thraupidae)

Abstract We assessed correlations between speciation rate and bill morphology in an ecologically diverse and continental-scale songbird radiation, the tanagers (Thraupidae). Our analyses showed that bill size, shape, and their evolutionary rates are not correlated with speciation rate. However, we did find evidence that each axis of variation in bill morphology diversifies at speciation events interspersed with periods of gradual evolution, consistent with a punctuated equilibrium model of character change. To determine correlations, we incorporated a time-calibrated molecular phylogeny and high-resolution three-dimensional surface scans of bill structure from museum study skins. Overall, our findings suggest that bill size and shape diversify in association with the speciation process, but not through any effect on the rate of speciation. Previous studies have shown other traits, such as song, ecological niche, and plumage do influence speciation and, ultimately, species richness in tanagers.

Point Cloud Registration for Measuring Shape Dependence of Soft Tissue Deformation by Digital Twins in Head and Neck Surgery

Introduction: A 2½ D point cloud registration method was developed to generate digital twins of different tissue shapes and resection cavities by applying a machine learning (ML) approach. This demonstrates the feasibility of quantifying soft tissue shifts. Methods: An ML model was trained using simulated surface scan data obtained from tumor resections in a pig head cadaver model. It hereby uses 438 2½ D scans of the tissue surface. Tissue shift was induced by a temperature change from 7.91 ± 4.1°C to 36.37 ± 1.28°C. Results: Digital twins were generated from various branched and compact resection cavities (RCs) and cut tissues (CT). A temperature increase induced a tissue shift with a significant volume increase of 6 mL and 2 mL in branched and compact RCs, respectively (p = 0.0443; 0.0157). The volumes of branched and compact CT were decreased by 3 and 4 mL (p < 0.001). In the warm state, RC and CT no longer fit together because of the significant tissue deformation. Although not significant, the compact RC showed a greater tissue deformation of 1 μL than the branched RC with 0.5 μL induced by the temperature change (p = 0.7874). The branched and compact CT forms responded almost equally to changes in temperature (p = 0.1461). Conclusions: The simulation experiment of induced soft tissue deformation using digital twins based on 2½ D point cloud models proved that our method helps to quantify shape-dependent tissue shifts.

Spectroscopic (FT-IR, FT-Raman, NMR and UV–vis), quantum calculation, molecular structure, solvent interaction, ADME and molecular docking investigation on 4-oxo-4h-1-benzopyran-2-carboxylic acid

The present work, spectroscopic and quantum computational study has been carried out for the molecule 4-oxo-4H-1-benzopyran-2-carboxylic acid. The stable conformer of the title molecule was identified using Potential Energy Surface (PES) scan. The structural and geometrical parameters of the stable conformer of the molecule were determined by Density Functional Theory (DFT) using B3LYP method along with the basis set 6-311++G(d,p) through Gaussian 09 W software. The theoretical and experimental investigations such as Vibrational (FT-IR and FT-Raman), UV–visible and NMR analysis were done. The FT-IR were recorded in the region of (4000–400 cm−1) and FT-Raman in the region of (4000–100 cm−1), and the vibrational bands were compared with the theoretical values. Carbon NMR and Proton NMR spectra have been analyzed in DMSO solution. The theoretical chemical shift values were determined using Gauge Independent Atomic Orbital (GIAO) method. The intermolecular and intra-molecular bonding of orbitals and transfer of charge were studied using the Natural Bond Orbital (NBO) analysis. The respective transitional study was done through UV–vis's spectra and theoretical values predicted using TD-DFT (Time Dependent – DFT) method for both gas and solvent (ethanol) state. HOMO (Highest Occupied Molecular Orbital) – LUMO (Lowest Unoccupied Molecular Orbital) energy gap results prove the exchange of charges inside the molecule. Molecular Electrostatic Potential (MEP) is used to identify the nucleophilic and electrophilic sites of the molecule. To check the bioactive nature of the title molecule the drug-likeness was determined. Molecular docking is used to analyze the biological activity of the title molecule. The distribution of torsional angles in a protein structure is viewed by the Ramachandran plots of the molecules.

Setup and intra-fractional motion measurements using surface scanning in head and neck cancer radiotherapy– A feasibility study

Background and purposeSurface-guided radiotherapy (SGRT) is applied to improve patient set-up and to monitor intra-fraction motion. Head and neck cancer (H&N) patients are usually fixated using 5-point thermoplastic masks, that are experienced as uncomfortable or even stressful. Therefore, the feasibility of irradiating H&N patients without a mask by using SGRT was examined. Material and methodsNineteen H&N patients were included in a simulation study. Once a week, before the standard treatment, a maskless treatment was simulated, using SGRT for setup and intrafraction motion monitoring. Initial patient setup accuracy and intrafraction motion was determined using ConeBeam CT (CBCT) images as well as SGRT before and after the (simulated) treatment. The clinical target volume to planning target volume (CTV-PTV) margin for intrafraction motion was calculated. Using patient questionnaires, the patient-friendliness H&N irradiation with and without mask was determined. ResultsMaskless setup with SGRT and CBCT was as accurate as with a mask. SGRT showed that intrafraction motion was gradual during the treatment. The CTV-PTV margin correcting for intrafraction motion was 1.7 mm for maskless treatment without interventions, and 1.2 mm if corrected for motions > 2 mm. For 19 % of fractions, the intrafraction motion, as detected by both SGRT and CBCT, was larger than 2 mm in at least one direction. Sixteen patients preferred maskless treatment, while 3 worried they would move too much. ConclusionsUsing SGRT and a standard head rest resulted in a patient-friendly treatment with accurate patient setup and acceptably small intrafraction motion for H&N patients.

Fast fingerprint scanning and chemical composition identification of a large-scale material surface by a combined HSI-LIBS operation

An experimental solution that combines hyperspectral imaging (HSI) and laser-induced breakdown spectroscopy (LIBS) applied to large-scale material surface chemical analysis is investigated..

Enhanced photoelectrochemical performance of quantum dot-sensitized solar cell using Cu2+ co-doped CdS and CdSe nanoscrystals.

Today, nanoscrystals are researched and developed very quickly because of their advantages in many areas of life. One of the potential applications is quantum dot-sensitized solar cells. This is a green, clean, environmentally friendly cell, and has been studied by scientists since 2000. In this study, we fabricated photoanodes with Cu2+ ions co-doped into cadmium sulfide (CdS) and cadmium selenide (CdSe) nanoscrystals by successive ionic layer adsorption and reaction, and chemical bath deposition methods to improve absorption spectral intensity of films. The results showed that the absorption intensity increased by eight times compared with our previous results on Cu2+ ions doped with CdSe nanoscrystals. The CdS:Cu2+ film is optimized at 2% doping, the efficiency is 4.6819%, and the current density is 27.3501 mA.cm-2, which is higher when compared with the Cu2+ ion only doped into the CdSe quantum dot (19.915 mA.cm-2). In addition, the composition of the photoanode was determined by surface and cross-sectional field-emission scanning electron microscope images, and the structure of the film was determined by X-ray diffraction, energy-dispersive X-ray spectroscopy mapping and X-ray photoelectron spectroscopy. Finally, the film's optical properties were studied by ultraviolet-visible spectroscopy, photoluminescence spectroscopy and electrochemical properties by electrochemical impedance spectroscopy. The results obtained have been discussed and presented in great detail.

Supercapacitance Performance of Mesoporous Mono- and Bi-Metallic Cobalt and Nickel Hydroxides Nanoflakes Chemically Deposited from Foam-Surfactant Liquid Crystal Dual Templates

Mesoporous 2D nanoflakes architectures of mono- and bi-metallic cobalt and nickel hydroxide (meso-Co-Ni(OH)2) hybrids were synthesized using novel chemical precipitation of foam-surfactant liquid crystal dual template (FSDT). The dissolved cobalt and nickel ions within the aqueous region of the Brij®78 surfactant template was reduced by the excess of sodium borohydride reducing agent that simultaneously generates excessive hydrogen foam as a double template. The physicochemical characterizations of the mono- and bi-metallic nanostructured Co-Ni(OH)2 hybrids performed using X-ray diffraction, surface area analyzer, scanning and transmission electrons microscopic techniques showed the formation of highly mesoporous hydroxides 2D nanoflakes architectures having an amorphous structure and surface area up to 253.50 m2/g. The electrochemical and supercapacitance evaluation of the mono-, and bi-metallic mesoporous hydroxides showed excellent Faradaic supercapacitance performance within a wider potential window and a higher charge and discharge rate. In particular the mesoporous monometallic of Co(OH)2, Ni(OH)2, bimetallic Co-Ni(OH)2 with Co/Ni ratios of (1:1), and (1:3), hydroxides showed total capacitances of 204, 869, 943, and 1384, F/g at charging current density of 5.0 A g−1 respectively and capacity retention rate of approximately 99.4% after 300 cycles. This suggests that these materials hold promise as electrode materials for energy storage applications.

Investigation of waste-derived and low-cost calcium oxide-based catalysts in co-pyrolysis of EFB-HDPE to produce high quality bio-oil

This study evaluated and compared the bio-oil yield produced from the co-pyrolysis of empty fruit bunch (EFB) and high-density polyethylene (HDPE) feedstock using four calcium oxide (CaO)-based catalysts. Three catalysts were derived from waste sources, namely, clamshell (CS), eggshell (ES), and chicken bone (CB), whereas Malaysia dolomite (MD) was extracted from limestone. Pure CaO catalyst served as a control experiment for comparison purposes. Surface area (BET), particle size (PSA), X-ray diffraction (XRD), and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX) examinations were used to compare all catalysts. BET and PSA demonstrated that waste-derived catalysts (CS, CB, ES) have the properties required for co-pyrolysis to produce good yield and quality of bio-oil, whilst XRD and SEM/EDX revealed the existence of CaO compound in each of the catalysts. The co-pyrolysis of EFB-HDPE was performed under controlled conditions in a fluidized-bed reactor. All co-pyrolysis parameters such as catalyst loading, feedstock loading, gas flow, and temperature were fixed for all reactions. The study explored the effect of each catalyst on the catalytic cracking of EFB-HDPE through the bio-oil yield and hydrocarbon composition from the reaction. The chemical composition of the bio-oil samples was analyzed by gas chromatography–mass spectrometry (GC-MS) analysis, whereas the bio-oil yield was calculated using mass-balance equation. The maximum oil yield was 26.07 wt% for ES, whereas pure CaO generated a 52.39% hydrocarbon composition, the highest among all catalysts, followed by ES.

Evaluation of Surface Roughness in Clear Silicon Fabricated Using Three Different Techniques: An In-vitro Study

Introduction: Anterior composite restorations present many aesthetic challenges for clinicians. Direct veneers provide chairside advantages such as evaluating tooth anatomy, shade selection, and correcting tooth morphology according to the patient’s desire. In today’s world, the use of digitalisation and 3D-printed models has grown. However, limitations of these are unknown and a research gap exists, with surface roughness being a major issue. Aim: To evaluate the surface roughness of clear silicon templates fabricated over 3D-printed models, blue inlay wax and dental stone. Materials and Methods: This in-vitro study utilised both quantitative and qualitative approaches. The study was conducted at the Department of Conservative Dentistry and Endodontics, Manubhai Patel Dental College and Hospital, Vadodara, Gujarat, India. The study was completed over three months. A total of 36 surfaces of clear silicone template (Exaclear) were obtained from two blocks each of 3D-printed model, blue inlay wax, and dental stone, measuring 30×10×10 mm. These blocks were divided into six units of 10×5 mm (N=36) and were divided into three groups: 1) 3D-printed model; 2) Blue inlay wax; 3) Dental stone. Surface roughness was evaluated using a surface roughness tester and Scanning Electron Microscope (SEM). Quantitative analysis of surface roughness was done using the surface roughness tester, and qualitative analysis was done using SEM. Statistical analysis was done using the posthoc Tukey Honest Significant Difference (HSD) test and statistical software SPSS Version 20.0. Results: The quantitative analysis showed the highest Roughness average (Ra) value mean±Standard Deviation (SD) for Group 1 (11.97±4.43 μm), followed by Group 3 (2.42±1.07 μm) and Group 2 (0.63±0.86 μm). SEM showed the presence of voids only in Group 1. Conclusion: Surface roughness of clear silicon template fabricated on wax surface is less as compared to templates fabricated on 3-D printed models.

Monolayers of a thiacalix[3]pyridine-supported molybdenum(0) tricarbonyl complex on Au(111): characterisation with surface spectroscopy and scanning tunneling microscopy.

Deposition of dome-shaped metal-organic complexes on metallic surfaces to produce well-defined single site catalysts is a novel approach combining aspects of homogeneous and heterogeneous catalysis. In order to investigate the bonding of small molecules to such systems, a molybdenum(0) tricarbonyl complex supported by a thiacalix[3]pyridine is synthesized and deposited on Au(111) and Ag(111) surfaces by vacuum evaporation. The resulting mono- and submonolayers are investigated with surface spectroscopy and STM. All of these methods indicate a parallel orientation of the molybdenum complex with respect to the surface. The vibrational properties and frequency shifts of the adsorbed complexes with respect to the bulk are evaluated with the help of conventional IR and IRRA spectroscopy, coupled to DFT calculations. Compared to a similar Mo(0) tricarbonyl complex supported by an azacalixpyridine ligand, the title complex exhibits a higher stability in the bulk and adsorbed to surfaces which goes along with a lower reactivity towards oxygen.

What can a morphometric study of unoperated children teach us about the natural history of metopic synostosis?

Outcomes of surgical repair of trigonocephaly are well reported in the literature, but there is a paucity of information on the natural history of unoperated children. The authors evaluated a group of unoperated children with metopic synostosis to describe the natural change in head shape over time. A database was screened for scans of children with unoperated trigonocephaly (2010-2021). Multisuture cases and those with a metopic ridge were excluded. Three-dimensional surface scans (3D stereophotogrammetry/CT) were used for morphological analysis. Nine previously published parameters were used: frontal angle (FA30°), anteroposterior (AP) volume ratio (APVR), AP area ratio (APAR), AP width ratios 1 and 2 (APWR1 and APWR2), and 4 AP diagonal ratios (30° right APDR [rAPDR30], 30° left APDR [lAPDR30], 60° right APDR [rAPDR60], and 60° left APDR [lAPDR60]). Ninety-seven scans were identified from a cohort of 316 patients with a single metopic suture, in which the male-to-female ratio was 2.7:1. Ages at the time of the scan ranged from 9 days to 11 years and were stratified into 4 groups: group 1, < 6 months; group 2, 6-12 months; group 3, 1-3 years; and group 4, > 3 years. Significant improvements were detected in 5 parameters (APVR, APAR, APWR1, rAPDR30, and lAPDR30) over time, whereas no significant differences were found in FA30, APWR2, rAPDR60, and lAPDR60 between age groups. Forehead shape (surface area and volume), as well as narrowing and anterolateral contour at the frontal points, differed significantly over time without surgery. However, forehead angulation, narrowing, and anterolateral contour at temporal points did not show significant differences. This knowledge will aid in surgical and parental decision-making.

Failure analysis of large and complex engine blades based on experimental research

On a certain day in December 2022, a GE90 engine equipped by an airline experienced a surge during flight. Ground inspection revealed broken blades of the 9-stage high-pressure compressor. To identify the cause of its fracture failure, the macroscopic fracture surface was first analyzed. Obvious fatigue crack propagation characteristics were found at the blade cross-section. Small pits formed by the impact were observed at the crack source location, indicating that the blade was first formed into a circular arc-shaped impact wound after being impacted by an external object. In the subsequent service process, under continuous vibration, fatigue cracks are formed at the impact point as the crack source and gradually propagate, ultimately leading to blade fracture and failure. To further explore the source of foreign objects causing impact damage, the surface scanning method using energy spectrum analysis was used. An enriched region of C element was found near the impact point. However, due to the lack of conditions for the formation of C combustion products at the compressor location, it can be considered that the foreign object may have come from external sources.

A Multimodal Point Cloud-Based Method for Tumor Localization in Robotic Ultrasound-Guided Radiotherapy.

Objectives: Part of the tumor localization methods in radiotherapy have poor real-time performance and may generate additional radiation. We propose a multimodal point cloud-based method for tumor localization in robotic ultrasound-guided radiotherapy, which only irradiates computed tomography (CT) during radiotherapy planning to avoid additional radiation. Methods: The tumor position was determined using the CT point cloud, and the red green blue depth (RGBD) point cloud was used to determine body surface scanning location corresponding to the tumor location. The relationship between the CT point cloud and RGBD point cloud was established through multi-modal point cloud registration. The point cloud was then used for robot tumor localization through coordinate transformation between camera and robot. Results: The maximum mean absolute error of the tumor location in the X, Y, and Z directions of the robot coordinate system were 0.781, 1.334, and 1.490 mm, respectively. The average point-to-point translation mean absolute error between the actual and predicted positions of the localization points was 1.847 mm. The maximum error in the random positioning experiment was 1.77 mm. Conclusion: The proposed method is radiation free and has real-time performance, with tumor localization accuracy that meets the requirements of radiotherapy. The proposed method, which potentially reduces the risks associated with radiation exposure while ensuring efficient and accurate tumor localization, represents a promising advancement in the field of radiotherapy.

Energy landscape of perylenediimide chromophoric aggregates.

Understanding the self-assembly of conjugated organic materials at the molecular level is crucial in their potential applications as active components in electronic and optoelectronic devices. The type of aggregation significantly influences the intriguing electronic and optical characteristics differing from their constituent molecules. Perylenediimides (PDIs), electron-deficient molecules exhibiting remarkable n-type semiconducting properties, are among the most explored organic fluorescent materials due to their high fluorescence efficiency, photostability, and optoelectronic properties. PDI derivatives are reported to form well-tailored supramolecular architectures: cofacial with minor slip (H-aggregates), staggered with major slip (J-aggregates), magic angle stacking (M-aggregates), rotated (X-aggregates), rotated orthogonal ((+)-aggregates), etc. H*-aggregates are defined here as an ideal case of H-aggregate with an eclipsed configuration. Although numerous reports regarding the formation and optical properties of various PDI aggregates are known, the key driving force within the PDI units guiding the self-assembly to form distinct aggregate systems remains elusive. To unravel the molecular-level mechanisms behind the self-assembly of PDI units by probing the intermolecular interactions, symmetry-adapted perturbation theory-based energy decomposition, potential energy surface scans, and non-covalent interaction index analyses were employed on PDI dimer models. Quantum theory of atoms in molecules and frontier molecular orbital analyses were implemented on the dimer models to comprehend the effect of heteroatoms and orbital interactions in stabilising the X-aggregates over the other PDI aggregate systems. Competition between the attractive and repulsive non-covalent interactions dictates a stability order of X > H > J > M > (+) > H* for the PDI aggregate system, while in the parent perylene system, the stability order was found to be X > (+) > H > M > J > H*.

Multi-set based model predictive control to explore large freshwater resources

Unmanned surface vehicles can become cutting-edge aquatic laboratories for real-time water quality assessment, evaluating the physical, chemical, and biological profiles of water to detect degradation in freshwater resources. The development of control strategies for surface scanning missions is essential for efficient and effective water resource management. This paper introduces novel exploration methods for analysis experiments. Our approach is founded on an optimizing target-set tracking controller and innovates by adopting a dynamic target-switching method. The target transitions to a further objective once the current target is assured, result in smoother system behavior, as shown by the simulations using the nonlinear model of a commercial surface vehicle tasked with covering a designated area of Heron Lake, located in Villeneuve d’Ascq. The method is implemented in two distinct ways: the first prioritizes passing through all the sets, while the second compromises between passing through and computational cost.