Stand-alone 3D Research Articles

Metastatic Lung Lesion Changes in Follow-up Chest CT: The Advantage of Deep Learning Simultaneous Analysis of Prior and Current Scans With SimU-Net.

Radiological follow-up of oncology patients requires the detection of metastatic lung lesions and the quantitative analysis of their changes in longitudinal imaging studies. Our aim was to evaluate SimU-Net, a novel deep learning method for the automatic analysis of metastatic lung lesions and their temporal changes in pairs of chest CT scans. SimU-Net is a simultaneous multichannel 3D U-Net model trained on pairs of registered prior and current scans of a patient. It is part of a fully automatic pipeline for the detection, segmentation, matching, and classification of metastatic lung lesions in longitudinal chest CT scans. A data set of 5040 metastatic lung lesions in 344 pairs of 208 prior and current chest CT scans from 79 patients was used for training/validation (173 scans, 65 patients) and testing (35 scans, 14 patients) of a standalone 3D U-Net models and 3 simultaneous SimU-Net models. Outcome measures were the lesion detection and segmentation precision, recall, Dice score, average symmetric surface distance (ASSD), lesion matching, and classification of lesion changes from computed versus manual ground-truth annotations by an expert radiologist. SimU-Net achieved a mean lesion detection recall and precision of 0.93±0.13 and 0.79±0.24 and a mean lesion segmentation Dice and ASSD of 0.84±0.09 and 0.33±0.22mm. These results outperformed the standalone 3D U-Net model by 9.4% in the recall, 2.4% in Dice, and 15.4% in ASSD, with a minor 3.6% decrease in precision. The SimU-Net pipeline achieved perfect precision and recall (1.0±0.0) for lesion matching and classification of lesion changes. Simultaneous deep learning analysis of metastatic lung lesions in prior and current chest CT scans with SimU-Net yields superior accuracy compared with individual analysis of each scan. Implementation of SimU-Net in the radiological workflow may enhance efficiency by automatically computing key metrics used to evaluate metastatic lung lesions and their temporal changes.

Comparative analysis of RNA 3D structure prediction methods: towards enhanced modeling of RNA-ligand interactions.

Accurate RNA structure models are crucial for designing small molecule ligands that modulate their functions. This study assesses six standalone RNA 3D structure prediction methods-DeepFoldRNA, RhoFold, BRiQ, FARFAR2, SimRNAand Vfold2, excluding web-based tools due to intellectual property concerns. We focus on reproducing the RNA structure existing in RNA-small molecule complexes, particularly on the ability to model ligand binding sites. Using a comprehensive set of RNA structures from the PDB, which includes diverse structural elements, we found that machine learning (ML)-based methods effectively predict global RNA folds but are less accurate with local interactions. Conversely, non-ML-based methods demonstrate higher precision in modeling intramolecular interactions, particularly with secondary structure restraints. Importantly, ligand-binding site accuracy can remain sufficiently high for practical use, even if the overall model quality is not optimal. With the recent release of AlphaFold 3, we included this advanced method in our tests. Benchmark subsets containing new structures, not used in the training of the tested ML methods, show that AlphaFold 3's performance was comparable to other ML-based methods, albeit with some challenges in accurately modeling ligand binding sites. This study underscores the importance of enhancing binding site prediction accuracy and the challenges in modeling RNA-ligand interactions accurately.

Three-dimensional carbon interdigitated ring array nanofibers for electrochemical detection of dopamine neurotransmitter

Dopamine (DA) neurotransmitter is a prominent component of the central nervous system and its deficiency contributes to several diseases, such as Parkinson’s disease and schizophrenia, which significantly influence the quality of life of affected individuals. This paper introduces a circular interdigitated ring electrode, the three-dimensional carbon interdigitated ring array nanofibers (3D C-IDRA NFs), for the detection of DA using amperometric detection. The study utilized cyclic voltammetry and chronoamperometry to investigate DA. The integration of carbon nanofibers (CNFs) with 3D C-IDRA demonstrated enhanced surface area, increased current peak, and superior performance compared to the standalone 3D C-IDRA electrode, as evidenced by a redox amplification factor of 2.94 and a collection efficiency of 81.1%. The results highlight that integrating CNFs with 3D C-IDRA improves the electrochemical performance in detecting DA neurotransmitter. Thus, this discovery elucidates the advantageous potential of the 3D C-IDRA NF electrode in a wide range of applications.

Cinematic rendering of non-traumatic thoracic aorta emergencies: a new look at an old problem.

Non-traumatic thoracic aorta emergencies are acute conditions associated with substantial morbidity and mortality. In the emergency setting, timely detection of aortic injury through radiological imaging is crucial for prompt treatment planning and favorable patient outcomes. 3D cinematic rendering (CR), a novel rendering algorithm for computed tomography (CT) image processing, allows for life-like visualization of spatial details and contours of highly complex anatomic structures such as the thoracic aorta and its vessels, generating a photorealistic view that not just adds to diagnostic confidence, but is especially useful for non-radiologists, including surgeons and emergency medicine physicians. In this pictorial review, we demonstrate the utility of CR in the setting of non-traumatic thoracic aorta emergencies through 10 cases that were processed at a standalone 3D CR station at the time of presentation, including its role in diagnosis and management.

Controlling Cell Organization in 3D Coculture Spheroids Using DNA Interactions.

The role of stromal and immune cells in transforming the tumor microenvironment is a key consideration in understanding tumor cell behavior and anticancer drug development. To better model these systems in vitro, 3D coculture tumor spheroids have been engineered using a variety of techniques including centrifugation to microwells, hanging drop, low adhesion cultures, and culture of cells in a microfluidic platform. Aside from using bioprinting, however, it has remained more challenging to direct the spatial organization of heterotypic cells in standalone 3D spheroids. To address this, we present an in vitro 3D coculture tumor model where we modulated the interactions between cancer cells and fibroblasts through DNA hybridization. When native heterotypic cells are simply mixed, the cell aggregates typically show cell sorting behavior to form phase separated structures composed of single cell types. In this work, we demonstrate that when MDA-MB-468 breast cancer and NIH/3T3 fibroblasts are directed to associate via complementary DNA, a uniform distribution of the two cell types within a single spheroid was observed. In contrast, in the absence of specific DNA interactions between the cancer cells and fibroblasts, individual clusters of the NIH/3T3 cells formed in each spheroid due to cell sorting. To better understand the effect of heterotypic cell organization on either cell-cell contacts or matrix protein production, the spheroids were further stained with anti-E-cadherin and antifibronectin antibodies. While the amounts of E-cadherin appeared to be similar between the spheroids, a significantly higher amount of fibronectin secretion was observed in the coculture spheroids with uniform mixing of two cell types. This result showed that different heterotypic cell distributions within 3D architecture can influence the ECM protein production that can again alter the properties of the tumor or tumor microenvironment. The present study thus describes the use of DNA templating to direct the organization of cells in coculture spheroids, which can provide mechanistic biological insight into how heterotypic distribution in tumor spheroids can influence tumor progression, metastasis, and drug resistance.

Comparison of Virtual Intersection and Occlusal Contacts between Intraoral and Laboratory Scans: An In-Vivo Study.

The inaccurate maxillomandibular relationship of virtual casts following alignment by the vestibular scan may result in intersection (intermesh penetration) between opposing dental arch surfaces. Intersection occurs at short interocclusal distances in the occlusal contact area (OCA) and may result in infra-occluded definitive restorations. The purpose of this clinical study was to compare initial (by the proprietary scanner software) and new alignments (by a standalone 3D software) of virtual casts regarding OCA and intersection failure. New alignments aimed to rectify intersections by refinement of occlusal contacts. The virtual casts of 30 patients following digital and conventional impression-taking were analyzed, which were acquired for single implant restoration in the posterior site. Digital impressions were performed by both IOS 1 (3M True Definition) and IOS 2 (TRIOS 3), either as complete- or partial-arch scans, respectively. Mounted gypsum casts were digitized as complete-arch by a laboratory scanner (LS) in enabled and disabled mode to avoid intersection [LS (+)/LS (-)]. All virtual casts were newly aligned by a 3D software. The difference of the OCA and the area of intersection were calculated for initial and new alignments, using interocclusal distance ranges of 0-100 μm, 0-10 μm or <0 μm (=intersection). The difference of the OCA was compared using a linear mixed model. The distribution of occlusal contact points per modality and alignment was assessed independently by three observers and estimated by inter- and intraclass correlation (ICC) coefficients. Virtual casts following initial alignment demonstrated intersections irrespective of the modality. The mean area of the intersection was most for IOS 2 (79.23 mm2), followed by IOS 1 (48.28 mm2), LS (-) (2.77 mm2), and LS (+) (2.01 mm2) in partial-arch scans. Complete-arch scans demonstrated an area of intersection of 70.63 mm2 for IOS 1 followed by 65.52 mm2 (IOS 2), 6.13 mm2 [LS (-)] and 2.76 mm2 [LS (+)]. Newly aligned scans showed no intersections. The overall distribution of occlusal contact points demonstrated moderate reliability (ICC 0.63). Good reliability could be observed (ICC 0.9) for LS (-) scans. Intersections in the area of occlusal contact points are a phenomenon restricted to virtual casts, which should be considered in CAD/CAM. Initial alignments of LS are less affected by this virtual phenomenon, and contact points may be more distinct according to their anatomic region compared to IOS. Furthermore, intersections can be rectified in a 3D software by adjustment of the maxillomandibular relationship.

Liver lesion changes analysis in longitudinal CECT scans by simultaneous deep learning voxel classification with SimU-Net.

The identification and quantification of liver lesions changes in longitudinal contrast enhanced CT (CECT) scans is required to evaluate disease status and to determine treatment efficacy in support of clinical decision-making. This paper describes a fully automatic end-to-end pipeline for liver lesion changes analysis in consecutive (prior and current) abdominal CECT scans of oncology patients. The three key novelties are: (1) SimU-Net, a simultaneous multi-channel 3D R2U-Net model trained on pairs of registered scans of each patient that identifies the liver lesions and their changes based on the lesion and healthy tissue appearance differences; (2) a model-based bipartite graph lesions matching method for the analysis of lesion changes at the lesion level; (3) a method for longitudinal analysis of one or more of consecutive scans of a patient based on SimU-Net that handles major liver deformations and incorporates lesion segmentations from previous analysis. To validate our methods, five experimental studies were conducted on a unique dataset of 3491 liver lesions in 735 pairs from 218 clinical abdominal CECT scans of 71 patients with metastatic disease manually delineated by an expert radiologist. The pipeline with the SimU-Net model, trained and validated on 385 pairs and tested on 249 pairs, yields a mean lesion detection recall of 0.86±0.14, a precision of 0.74±0.23 and a lesion segmentation Dice of 0.82±0.14 for lesions > 5mm. This outperforms a reference standalone 3D R2-UNet mdel that analyzes each scan individually by ∼50% in precision with similar recall and Dice score on the same training and test datasets. For lesions matching, the precision is 0.86±0.18 and the recall is 0.90±0.15. For lesion classification, the specificity is 0.97±0.07, the precision is 0.85±0.31, and the recall is 0.86±0.23. Our new methods provide accurate and comprehensive results that may help reduce radiologists' time and effort and improve radiological oncology evaluation.

An evaluation of concordance between linear measurements obtained from conventional, digital and reconstructed three-dimensional printed orthodontic models: An in vitro study

Abstract Objective: To evaluate the potential use of digital and reconstructed three-dimensional printed models as an alternative to conventional plaster models by assessing the accuracy of their linear measurements. Methodology: Pre-treatment plaster models of 45 patients were selected from the archives of the Department of Orthodontics. Each physical plaster model was scanned and digitized using a three-dimensional (3D) laser surface scanning system (inEOS X5, Dentsply Sirona, Bensheim, Germany). The scanned STL files were later used to reconstruct models by 3D printing using Figure4® standalone 3D printer (3D systems, Rock Hill, South Carolina). Measurements of teeth 11 and 16, the transverse width of the upper jaw between the first molars (MM - intermolar width) and canines (CC - intercanine width) were done manually using a digital vernier caliper (Mitutoyo, Kawasaki, Japan), and the CAD Assistant software (Open cascade, Guyancourt, France). Intra examiner data, Intraobserver variability, and measurement accuracy were evaluated using Intraclass Correlation Coefficient (ICC) analysis was done using SPSS 20.0. Results: The intraclass correlation coefficients were &gt;0.8 indicating high reproducibility and reliability. Significant differences were found between the physical and the digital models but to a small proportion which were deemed not clinically relevant. Conclusion: Both the digital models and reconstructed three-dimensional printed models using Figure4® technology were clinically permissible in terms of accuracy and reproducibility. The digital storage, transmission, and treatment planning in an environmentally friendly manner should promote digital over conventional records.

3D Modelling of Meteorite from Astomulyo Village, Lampung, Indonesia by Close Range Photogrammetry (CRP) Methods

This research was conducted to 3D model our meteorite collection based on photo-capturing. This meteorite are from Astomulyo, Central Lampung, Indonesia. It entry the earth's atmosphere and was found on January 28, 2021. The chance of object degradation nearly appears over time, so It is very urgent to obtain the 3D model of the object for further research necessary. 3D modelling was carried out using a non-metric camera to conduct the close-range photogrammetry method. It applies to modelling the objects based on photo data using the concept of collinearity by using a central projection system on the camera to record. The collinearity will produce an object point between the camera center and the object cloud point. Hence, this process forms the object model from the appropriate image projection, the tie point with the triangular irregular network model. As a result, it produces the DTM (Digital Terrain Model) object formation using stand-alone photogrammetric software, raster graphics, and 3D modelling software.

Bioink Platform Utilizing Dual-Stage Crosslinking of Hyaluronic Acid Tailored for Chondrogenic Differentiation of Mesenchymal Stromal Cells.

3D bioprinting often involves application of highly concentrated polymeric bioinks to enable fabrication of stable cell-hydrogel constructs, although poor cell survival, compromised stem cell differentiation, and an inhomogeneous distribution of newly produced extracellular matrix (ECM) are frequently observed. Therefore, this study presents a bioink platform using a new versatile dual-stage crosslinking approach based on thiolated hyaluronic acid (HA-SH), which not only provides stand-alone 3D printability but also facilitates effective chondrogenic differentiation of mesenchymal stromal cells. A range of HA-SH with different molecular weights is synthesized and crosslinked with acrylated (PEG-diacryl) and allylated (PEG-diallyl) polyethylene glycol in a two-step reaction scheme. The initial Michael addition is used to achieve ink printability, followed by UV-mediated thiol-ene reaction to stabilize the printed bioink for long-term cell culture. Bioinks with high molecular weight HA-SH (>200kDa) require comparably low polymer content to facilitate bioprinting. This leads to superior quality of cartilaginous constructs which possess a coherent ECM and a strongly increased stiffness of long-term cultured constructs. The dual-stage system may serve as an example to design platforms using two independent crosslinking reactions at one functional group, which allows adjusting printability as well as material and biological properties of bioinks.

Fabrication and characterization of titanium-alloy 3D printed solenoid inductors and their sensor applications

Recent progress in 3D printing has brought many interests in developing functional devices in various applications by enabling the exploration of complex 3D structures. This paper presents the first fully metal printed standalone 3D solenoid microinductors using a high-power laser with a biocompatible Ti-alloy. Fine powder-based 6AL-4V Eli Titanium was directly printed using an automated gantry laser system with 60 μm resolution to form the inductors without any substrate. A substrate-less 10-turn solenoid as a testbed was printed out and characterized, and additional designs of 20 and 40 turn inductors were further explored. The wire of the inductor was designed to have a 700-micron square cross-section and a winding gap of 300 microns. The successfully fabricated 10-turn titanium-alloy solenoid inductor showed an average inductance of 130 nH, a low-frequency resistance of 0.8 ohms at 0.3 MHz, and a quality factor of 10.5 at 30 MHz respectively. Additional electrodeposition of copper to the 10-turn inductor demonstrated process compatibility with the conventional micromachining process. The standalone inductor printing method saves a significant volume from where the conventional substrate dimensions often take more than the volume of the device. Also, the standalone inductor can directly be used as a sensor device. Examples of force-displacement sensing applications were presented using the 10-turn and 19-turn round edge solenoid inductors.

Aerodynamic limits of gas turbine compressor during high air offtakes for minimum load extension

Renewable energy sources (RES) have become a favoured alternative to fossil fuel energy generation that has been driven by environmental concerns. Their intermittent nature has meant that gas turbines have remained relevant to support them as a backup. Current grid operation requires gas turbines to operate at as low power as possible when their demand drops, and also ramp-up quickly when power generation from renewables declines. Air extraction from a gas turbine compressor can address the first requirement, as this mechanism reduces the load or power of the engine while storing the air for further pressurised reinjection, related to ramp-up rate improvements. This study demonstrates the aerodynamic implications and the limits to air extraction behind the last stage of the compressor, to achieve further minimum load reduction. To achieve this, a zero-dimensional (0D) analytical model of an engine at design and off-design conditions (air extraction) has been used to determine the boundary conditions for a 3D compressor Computational Fluid Dynamics (CFD) model. The multi-stage CFD model shows the aerodynamic implications of low to high air extractions that are limited by choke, high flow separation, and loss in the pressure at the hub region of OGV and last stage stator. As such, the back of the compressor was more affected than the earlier stages. Based on these, the limit of flow extraction is 18% (of the compressor discharge). The compressor of the analytical engine model showed similarity in trends for comparable conditions with the stand-alone 3D compressor, however, more optimistic than the latter. The work has shown that the compressor is capable of high airflow extractions to reduce the minimum load further.

Three Dimension Scanning using Infrared Coded Light

In this competitive market, reverse engineering is introduced to shorten a new product development time by digitizing an existing product for rapid redesign. In this project, a low cost and standalone 3D scanner is being developed to achieve this purpose. Research is done comparing advantages and limitation of different hardware and method for 3D scanning. Scanner is assisted by automated rotating and illumination scanning platform to improve its performance. Software is developed for scanning of object using a Red-Green-Blue-Depth (RGBD) camera. The scanned result is processed and refined using global and local registration method. Poisson surface reconstruction is performed on the processed point clouds for generating triangular mesh. This scanner able to scan the object with the accuracy up to 5mm with computational time around 25 minutes.

A recyclable CNC-milled microfluidic platform for colorimetric assays and label-free aged-related macular degeneration detection

We report the development of a simple, low-cost, and eco-friendly stand-alone 3D microfluidic chemical sensing platform capable of colorimetric and biochemical analyses at the same time. The microfluidic cellulose microfiber (μCM) chip was prototyped by injecting 10% CM mixtures on computer numeric control (CNC)-milled substrates. We show that the μCM chip has a 3-fold faster flow rate than conventional microfluidic paper-based analytical devices and is a recyclable platform that could perform basic microfluidic experiments. The colorimetric assays of the μCM chip can successfully detect clinically relevant concentrations of albumin (R2 = 0.9994) and glucose (R2 = 0.9464). The gold nanoparticle-induced surface-enhanced Raman scattering (SERS) label-free bioassay of μCM chips can enhance the Raman signal by 5.15 × 108 and a sensitivity of 0.94 (10 pM–1 mM for CV molecules) with an excellent stability of <5%. We can detect the presence of exudative age-related macular degeneration (AMD) from human aqueous humors with >96% clinical sensitivity and >78% clinical specificity (87% accuracy) from principal component linear discriminant analysis (PC-LDA) model-based multivariate statistical analysis methods.

An Evaluation of an Apple Canopy Density Mapping System for a Variable-rate Sprayer

This paper proposes methods for evaluating an apple canopy density mapping system as an input for a variable-rate sprayer for both trellis-structured (2D) and standalone (3D) apple orchards. The mobile terrestrial system used in this paper consists of a 2D LiDAR (Light Detection and Ranging), three RGB-D cameras and a GPS-RTK module. A 3D point cloud was generated for 2D or 3D tree row, then converted to a 2D matrix with density distribution information for the variable-rate sprayer. Quad frames were placed in the trees to gain ground truth data for GPS validation and canopy density. They were extracted from the 3D point cloud by intensity thresholding and RANSAC along with their locations and timestamps.Five evaluation methods are discussed in this paper to validate the robustness and repeatability of the canopy density mapping system: Quad locations will be used to evaluate GPS accuracy; Quad density deviation and overall deviation in multiple passes will evaluate the repeatability. Then manual classified quad density will be compared with automatic density extraction to evaluate correlation; The misalignment of the point cloud from both sides of a tree row exists but this paper compares between two sides of the same row. The result indicates that it might be sufficient to scan from one side only to halve the field work.The proposed system will help the decision making in a variable-rate sprayer. The evaluation methods are practical, easy to be applied in similar approaches to map canopy density.

A stand-alone 3D muon tracking system based on Silicon Photomultipliers

We present a muon tracking system based on the use of plastic scintillator strips and Silicon Photomultipliers (SiPMs). Originally intended to be used mainly in outreach activities, the detector became an effective instrument to perform muon flux intensity measurements and for muon transmission imaging applications. It consists of two independent orthogonal views, each one made of 10 planes and containing 10 detection channels per plane. A custom electronics has been designed to bias and readout all the 200 SiPMs in the detector, to generate the trigger logic pattern and to control the working parameters. Thanks to an on-board data acquisition system, standalone data taking is possible with the addition of a computer. Commissioning and performance of the detector are presented, along with preliminary results concerning the first data taking on Saadiyat Island, Abu Dhabi, with the aim of measuring the local cosmic ray flux and to assess its muon transmission imaging capability.

Real-time 3D ultrasound based motion tracking for the treatment of mobile organs with MR-guided high-intensity focused ultrasound

Introduction: Magnetic resonance-guided high-intensity focused ultrasound (MRgHIFU) treatments of mobile organs require locking the HIFU beam on the targeted tissue to maximise heating efficiency. We propose to use a standalone 3 D ultrasound (US)-based motion correction technique using the HIFU transducer in pulse-echo mode. Validation of the method was performed in vitro and in vivo in the liver of pig under MR-thermometry.Methods: 3 D-motion estimation was implemented using ultrasonic speckle-tracking between consecutive acquisitions. Displacement was estimated along four sub-apertures of the HIFU transducer by computing the normalised cross-correlation of backscattered signals followed by a triangulation algorithm. The HIFU beam was steered accordingly and energy was delivered under real-time MR-thermometry (using the proton resonance frequency shift method with online motion compensation and correction of associated susceptibility artefacts). An MR-navigator echo was used to assess the quality of the US-based motion correction.Results: Displacement estimations from US measurements were in good agreement with 1 D MR-navigator echo readings. In vitro, the maximum temperature increase was improved by 37% as compared to experiments performed without motion correction and temperature distribution remained much more focussed. Similar results were reported in vivo, with an increase of 35% on the maximum temperature using this US-based HIFU target locking.Conclusion: This standalone 3D US-based motion correction technique is robust and allows maintaining the HIFU focal spot in the presence of motion without adding any burden or complexity to MR thermal imaging. In vitro and in vivo results showed about 35% improvement in heating efficiency when focus position was locked on the target using the proposed technique.

Vehicle dynamics control by using a three-dimensional stabilizer pendulum system

ABSTRACTActive safety systems of a vehicle normally work well on tyre–road interactions, however, these systems deteriorate in performance on low-friction road conditions. To combat this effect, an innovative idea for the yaw moment and roll dynamic control is presented in this paper. This idea was inspired by the chase and run dynamics animals like cheetahs in the nature; cheetahs have the ability to swerve while running at very high speeds. A cheetah controls its dynamics by rotating its long tail. A three-dimensional stabilizer pendulum system (3D-SPS) resembles the rotational motion of the tail of a cheetah to improve the stability and safety of a vehicle. The idea has been developed in a stand-alone 3D stabilizer pendulum system as well as in an integrated control system, which consists of an ordinary differential braking direct yaw control (DYC) and active steering control that is assisted by the 3D-SPS. The performance of the proposed 3D-SPS has been evaluated over a wide range of handling manoeuvres by using a comprehensive numerical simulation. The results show the advantage of 3D-SPS over conventional control approaches, which are ineffective on low-friction road conditions and high lateral acceleration manoeuvres. It should however be noted that the best vehicle dynamics performance is obtained when an integrated 3D-SPS and DYC and AFS is utilised.

Development, validation and application of multi-point kinetics model in RELAP5 for analysis of asymmetric nuclear transients

Point kinetics approach in system code RELAP5 limits its use for many of the reactivity induced transients, which involve asymmetric core behaviour. Development of fully coupled 3D core kinetics code with system thermal-hydraulics is the ultimate requirement in this regard; however coupling and validation of 3D kinetics module with system code is cumbersome and it also requires access to source code. An intermediate approach with multi-point kinetics is appropriate and relatively easy to implement for analysis of several asymmetric transients for large cores. Multi-point kinetics formulation is based on dividing the entire core into several regions and solving ODEs describing kinetics in each region. These regions are interconnected by spatial coupling coefficients which are estimated from diffusion theory approximation. This model offers an advantage that associated ordinary differential equations (ODEs) governing multi-point kinetics formulation can be solved using numerical methods to the desired level of accuracy and thus allows formulation based on user defined control variables, i.e., without disturbing the source code and hence also avoiding associated coupling issues. Euler's method has been used in the present formulation to solve several coupled ODEs internally at each time step. The results have been verified against inbuilt point-kinetics models of RELAP5 and validated against 3D kinetics code TRIKIN. The model was used to identify the critical break in RIH of a typical large PHWR core. The neutronic asymmetry produced in the core due to the system induced transient was effectively handled by the multi-point kinetics model overcoming the limitation of in-built point kinetics model of RELAP5 and standalone 3D core kinetics codes.

A stand-alone pressure-driven 3D microfluidic chemical sensing analytic device

This study introduces a new stand-alone pressure-driven 3D microfluidic chemical sensing analytic device (PD-PAD), fabricated by enclosing a cover substrate and inserting a void-channeled substrate on a conventional capillary-driven microfluidic paper-based analytical device (CD-PAD). Adhesive cold-laminating film and filter paper were used as a substrate. The flow rates of 3D PD- and CD-PAD platforms were compared through five different character-shaped microfluidic channels. A single 60-μL drop of fluid inducing 0.4mbar of pressure showed that the PD-PAD was roughly 300-fold faster than the CD-PAD. The more input pressure in the PD-PAD increased, the more flow increased. The structures with the curved channels less than 90° led to a decreased flow rate in the CD-PAD, but did not affect the PD-PAD. The superior flow rate in the PD-PAD was likely due to the concurrence of the pressure-driven and capillary-driven flows. The glucose and albumin concentrations with a clinically relevant range and pH levels were successfully detected. Therefore, a stand-alone 3D microfluidic PD-PAD platform has great potential for assessing for the presence of diseases in very urgent situations such as the operating room or for use in low-cost and fast point-of-care applications.