Current Acquisition Methods Research Articles

Development of an Efficient Synthetic Process for Irisquinone

AbstractIrisquinone is a tumor radiotherapy sensitizer and has been found to have broad-spectrum antitumor activity in recent years. The current acquisition method of extracting and purifying from semen irisis has greatly limited its wide application and activity study deeply. In this work an efficient route for the synthesis of the irisquinone was investigated to solve the source of it. The target compound was synthesized by 5-step reactions to Wittig reaction, reduction, oxidation, Wittig reaction, and oxidation using 3,5-dimethoxycarboxaldehyde as the starting material with an overall yield of 48%. The key factors such as the ratio of raw materials, temperatures, solvents, reaction times, and types of base for the main reactions were optimized. In addition, the deprotection and reduction were completed with Pd/C catalytic simultaneously when compound 2 was synthesized from compound 1. In the last reaction, the 3,5-dimethoxybenzene moiety of compound 4 was directly oxidized to 6-methoxy-1,4-benzoquinone by K3[Fe(CN)6]/H2O2 without the need to selectively remove the methyl protecting group, which were the innovative points in the experimental route design of the irisquinone synthesis. This work has opened new perspectives for the artificial synthesis and the development of irisquinone.

AstroYOLO: A hybrid CNN–Transformer deep-learning object-detection model for blue horizontal-branch stars

Abstract Blue horizontal-branch stars (BHBs) are ideal tracers for studying the Milky Way (MW) due to their bright and nearly constant magnitude. However, an incomplete screen of BHBs from a survey would result in bias of estimation of the structure or mass of the MW. With surveys of large sky telescopes like the Sloan Digital Sky Survey (SDSS), it is possible to obtain a complete sample. Thus, detecting BHBs from massive photometric images quickly and effectually is necessary. The current acquisition methods of BHBs are mainly based on manual or semi-automatic modes. Therefore, novel approaches are required to replace manual or traditional machine-learning detection. The mainstream deep-learning-based object-detection methods are often vanilla convolutional neural networks whose ability to extract global features is limited by the receptive field of the convolution operator. Recently, a new Transformer-based method has benefited from the global receptive field advantage brought by the self-attention mechanism, exceeded the vanilla convolution model in many tasks, and achieved excellent results. Therefore, this paper proposes a hybrid convolution and Transformer model called AstroYOLO to take advantage of the convolution in local feature representation and Transformer’s easier discovery of long-distance feature dependences. We conduct a comparative experiment on the 4799 SDSS DR16 photometric image dataset. The experimental results show that our model achieves 99.25% AP@50, 93.79% AP@75, and 64.45% AP@95 on the test dataset, outperforming the YOLOv3 and YOLOv4 object-detection models. In addition, we test on larger cutout images based on the same resolution. Our model can reach 99.02% AP@50, 92.00% AP@75, and 61.96% AP@95 respectively, still better than YOLOv3 and YOLOv4. These results also suggest that an appropriate size for cutout images is necessary for the performance and computation of object detection. Compared with the previous models, our model has achieved satisfactory object-detection results and can effectively improve the accuracy of BHB detection.

Research Progress of Nervonic Acid Biosynthesis.

Nervonic acid (NA) is a very-long-chain monounsaturated fatty acid with great application values. It plays a vital role in the development of brain nervous system and the treatment of neurological diseases, so it has attracted much attention from all walks of life. Although NA has a wide range of sources, its current acquisition methods are still mainly relied on chemical synthesis and plant extraction, which are challenging to meet the market and green industry demands, limiting its development and application. In recent years, with the rapid development of synthetic biology technology, NA biosynthesis has become an alternative production strategy. In this study, we summarize the physicochemical properties, pharmacological activities, resources, biosynthetic pathways and heterologous biosynthesis of NA, and discuss the challenges and prospects of NA biosynthesis. The application prospects of cell-free systems and retrobiosynthesis in NA synthesis were also reviewed.

Phase-constrained reconstruction method with compressed sensing for multi-parametric quantitative magnetic resonance imaging

PurposeIn magnetic resonance imaging (MRI), STAGE method is a novel quantitative imaging method to generate multi-parametric quantitative images during single one scan. Due to the use of multiple echo sequences with double flip angles, current acquisition methods consume a lot of time, which limits the clinical application of these methods. To shorten the acquisition time of the STAGE method, a phase-constrained CS reconstruction method combined with parallel imaging (PI) is proposed in this paper. MethodsThe phase consistency between the acquisition data from different flip angles (FA) is exploited to reconstruct STAGE sequences. The phase from the first flip acquisition is used as the constraint term in the CS model to reconstruct the acquisition data from the second flip angle. To solve the optimization problem with multiple regularization in the CS model,the primal–dual algorithm is applied to the optimization problem. In vivo data from 10 volunteers are reconstructed, and the reconstruction results are compared with those of the conventional l1-iterative self-consistent parallel imaging reconstruction from arbitrary k-space (l1-SPIRiT) method. Also, quantitative comparisons are performed with multiple quantitative matrics including structural similarity index measure (SSIM), peak signal-to-noise ratio (pSNR) for the contrast image, normalized root-mean-square error (NRMS), and linear relationship value. ResultsThe experimental results demonstrate that the proposed method outperforms the conventional l1-SPIRiT method under different acceleration factors. Meanwhile, the proposed method achieves better SSIM and higher pSNR than the conventional l1-SPIRiT for T1 weighted (T1W) images. Besides, the quantitative mapping obtained by the proposed method under different acceleration factors have better consistency with the reference one. Moreover, the proposed method enables further acceleration of the image acquisition of STAGE sequences. ConclusionThe proposed phase-constrained reconstruction method with compressed sensing accelerates STAGE without compromising the image quality, which enables higher acceleration than the conventional method.

Predicting F v /F m and evaluating cotton drought tolerance using hyperspectral and 1D-CNN.

The chlorophyll fluorescence parameter Fv/Fm is significant in abiotic plant stress. Current acquisition methods must deal with the dark adaptation of plants, which cannot achieve rapid, real-time, and high-throughput measurements. However, increased inputs on different genotypes based on hyperspectral model recognition verified its capabilities of handling large and variable samples. Fv/Fm is a drought tolerance index reflecting the best drought tolerant cotton genotype. Therefore, Fv/Fm hyperspectral prediction of different cotton varieties, and drought tolerance evaluation, are worth exploring. In this study, 80 cotton varieties were studied. The hyperspectral cotton data were obtained during the flowering, boll setting, and boll opening stages under normal and drought stress conditions. Next, One-dimensional convolutional neural networks (1D-CNN), Categorical Boosting (CatBoost), Light Gradient Boosting Machines (LightBGM), eXtreme Gradient Boosting (XGBoost), Decision Trees (DT), Random Forests (RF), Gradient elevation decision trees (GBDT), Adaptive Boosting (AdaBoost), Extra Trees (ET), and K-Nearest Neighbors (KNN) were modeled with F v /F m. The Savitzky-Golay + 1D-CNN model had the best robustness and accuracy (RMSE = 0.016, MAE = 0.009, MAPE = 0.011). In addition, the F v /F m prediction drought tolerance coefficient and the manually measured drought tolerance coefficient were similar. Therefore, cotton varieties with different drought tolerance degrees can be monitored using hyperspectral full band technology to establish a 1D-CNN model. This technique is non-destructive, fast and accurate in assessing the drought status of cotton, which promotes smart-scale agriculture.

Electric Window Regulator Based on Intelligent Control

In order to effectively solve the problem of installation cost of automobile electric windows and the safety of passengers, the window regulator of the car must have an intelligent control function. For example, most automobile windows now have an anti-pinch function. In this paper, the model of DC brushed motor is analyzed, an intelligent control scheme for automotive power windows is proposed, and the relationship between current ripple and window travel, motor current and external resistance are verified. In the hardware design, S9S12G128 is the main control chip, and the motor current acquisition method is designed. In the software design, intelligent control methods such as current integration method, adaptive and self-learning algorithm and intelligent speed regulation method are proposed to realize functions such as automatic window opening and closing, intelligent anti-pinch and intelligent speed regulation. After many experiments, the results prove the feasibility of the above methods and the stability of the system.

A new method of culturing rat bone marrow endothelial progenitor cells in vitro.

Endothelial progenitor cells (EPCs) play an important role in the re-endothelialization of ischemic cerebrovascular disease. However, the current acquisition method has some deficiencies. This study aimed to design a new and practical method for obtaining EPCs. Bone marrow was obtained autologously from the right tibia of living rats. Briefly, the right tibia bone was carefully exposed and two holes (1 mm in diameter) were made in the tuberosity and lower one-third of the tibia, respectively. A PE-50 catheter and syringe (5 mL) were inserted through the holes to aspirate the bone marrow. Bone marrow mononuclear cells (BMMCs) were isolated by density-gradient centrifugation with Ficoll and counted. Adherent cell culture continued for 2 weeks, and the medium was replaced every 3 days. During the first days of culture, adherent cells formed a monolayer, consisting predominantly of small-sized cells. Single large cells with endothelial morphology were observed. On day 4, the nonadherent cells were removed, and the adherent cells were left for further culture. On day 6-7, a proliferating population of round cells formed clusters in the culture chamber, and morphological analysis revealed a homogeneous population of colony-forming units (CFUs). Large, flat cells with endothelial morphology sprouted from the CFUs, which had nearly disappeared by day 14 of culture. The adherent cells were positive for CD133 and vascular endothelial growth factor receptor 2 (VEGFR2), internalized acetylated low-density lipoprotein, and bound ulex europaeus-agglutinin-I, but were negative for CD45, which correlated with the endothelial morphology and ability to form capillaries of EPCs. Our results are direct evidence that mononuclear cells (MCS) from living rat bone marrow can be used to culture EPCs in vitro under certain culture conditions, providing a new method for the further study of autologous EPC transplantation.

Imaging biomarkers of posttraumatic epileptogenesis.

Traumatic brain injury (TBI) affects 2.5 million people annually within the United States alone, with over 300000 severe injuries resulting in emergency room visits and hospital admissions. Severe TBI can result in long-term disability. Posttraumatic epilepsy (PTE) is one of the most debilitating consequences of TBI, with an estimated incidence that ranges from 2% to 50% based on severity of injury. Conducting studies of PTE poses many challenges, because many subjects with TBI never develop epilepsy, and it can be more than 10years after TBI before seizures begin. One of the unmet needs in the study of PTE is an accurate biomarker of epileptogenesis, or a panel of biomarkers, which could provide early insights into which TBI patients are most susceptible to PTE, providing an opportunity for prophylactic anticonvulsant therapy and enabling more efficient large-scale PTE studies. Several recent reviews have provided a comprehensive overview of this subject (Neurobiol Dis, 123, 2019, 3; Neurotherapeutics, 11, 2014, 231). In this review, we describe acute and chronic imaging methods that detect biomarkers for PTE and potential mechanisms of epileptogenesis. We also describe shortcomings in current acquisition methods, analysis, and interpretation that limit ongoing investigations that may be mitigated with advancements in imaging techniques and analysis.

Correction of magnetic field inhomogeneity effects for fast quantitative susceptibility mapping.

Quantitative susceptibility mapping (QSM) provides information about tissue composition and organization. However, current acquisition methods can be quite time consuming, limiting the use of QSM in studies and in monitoring dynamic events. In this work, time efficient spiral acquisitions are combined with a model-based image reconstruction approach. Magnetic field inhomogeneity artifacts are corrected to obtain full brain susceptibility maps. Magnetic field maps, capturing the magnetic field inhomogeneity distribution due to non-tissue sources (background field), were estimated from a calibration scan. Tissue phase information present in the background field maps was identified using variable spherical mean value filtering and removed from the estimated field maps. The resulting background field maps were then used in the image reconstruction to correct the magnetic field inhomogeneity artifacts. Images were acquired on a 3T system with a 3D spiral-in acquisition based on a rotated stack of spirals. For comparison, standard gradient echo images were also acquired. Susceptibility maps were obtained for both acquisitions using a dipole inversion algorithm based on a compressed sensing compensated formulation with wavelet and total variation penalties. Susceptibility maps obtained with the spiral acquisition and the model-based reconstruction agree with the ones obtained with the spin-warp gradient echo acquisition. Using the 3D spiral acquisition, full brain susceptibility maps at the resolution of 1mm isotropic are obtained in 23s CONCLUSIONS: Image distortions and blurring due to magnetic field inhomogeneity are removed while maintaining tissue magnetic susceptibility information, resulting in QSM maps in much shorter acquisition time.

Dual-Energy CT: New Horizon in Medical Imaging.

Dual-energy CT has remained underutilized over the past decade probably due to a cumbersome workflow issue and current technical limitations. Clinical radiologists should be made aware of the potential clinical benefits of dual-energy CT over single-energy CT. To accomplish this aim, the basic principle, current acquisition methods with advantages and disadvantages, and various material-specific imaging methods as clinical applications of dual-energy CT should be addressed in detail. Current dual-energy CT acquisition methods include dual tubes with or without beam filtration, rapid voltage switching, dual-layer detector, split filter technique, and sequential scanning. Dual-energy material-specific imaging methods include virtual monoenergetic or monochromatic imaging, effective atomic number map, virtual non-contrast or unenhanced imaging, virtual non-calcium imaging, iodine map, inhaled xenon map, uric acid imaging, automatic bone removal, and lung vessels analysis. In this review, we focus on dual-energy CT imaging including related issues of radiation exposure to patients, scanning and post-processing options, and potential clinical benefits mainly to improve the understanding of clinical radiologists and thus, expand the clinical use of dual-energy CT; in addition, we briefly describe the current technical limitations of dual-energy CT and the current developments of photon-counting detector.

BRDF Representation and Acquisition

AbstractPhotorealistic rendering of real world environments is important in a range of different areas; including Visual Special effects, Interior/Exterior Modelling, Architectural Modelling, Cultural Heritage, Computer Games and Automotive Design.Currently, rendering systems are able to produce photorealistic simulations of the appearance of many real‐world materials. In the real world, viewer perception of objects depends on the lighting and object/material/surface characteristics, the way a surface interacts with the light and on how the light is reflected, scattered, absorbed by the surface and the impact these characteristics have on material appearance. In order to re‐produce this, it is necessary to understand how materials interact with light. Thus the representation and acquisition of material models has become such an active research area.This survey of the state‐of‐the‐art of BRDF Representation and Acquisition presents an overview of BRDF (Bidirectional Reflectance Distribution Function) models used to represent surface/material reflection characteristics, and describes current acquisition methods for the capture and rendering of photorealistic materials.

Highly accelerated dynamic contrast enhanced imaging

Dynamic contrast-enhanced imaging provides unique physiological information, notably the endothelial permeability (K(trans)), and may improve the diagnosis and management of multiple pathologies. Current acquisition methods provide limited spatial-temporal resolution and field-of-view, often preventing characterization of the entire pathology and precluding measurement of the arterial input function. We present a method for highly accelerated dynamic imaging and demonstrate its utility for dynamic contrast-enhanced modeling. We propose a novel Poisson ellipsoid sampling scheme and enforce multiple spatial and temporal l1-norm constraints during image reconstruction. Retrospective and prospective analyses were performed to validate the approach. Retrospectively, no mean bias or diverging trend was observed as the acceleration rate was increased from 3× to 18×; less than 10% error was measured in K(trans) at any individual rates in this range. Prospectively accelerated images at a rate of 36× enabled full brain coverage with 0.94 × 0.94 × 1.9 mm(3) spatial and 4.1 s temporal resolutions. Images showed no visible degradation and provided accurate K(trans) values when compared to a clinical population. Highly accelerated dynamic MRI using compressed sensing and parallel imaging provides accurate permeability modeling and enables full brain, high resolution acquisitions.

Adaptive image acquisition by autodefocusing

We present an adaptive image-acquisition methodology by replacing the traditional birefringent filter with slight out-of-focus blur generated by the camera lens. Because many cameras already have adjustable lenses and autofocus systems, our method can exploit existing hardware by simply changing the focusing strategy. During the image acquisition, the optimal defocus setting is automatically adapted to the power spectrum of the scene, which is evaluated by a generic autocorrelation model. We develop a criterion to estimate reconstruction errors without the baseband knowledge of the scene. This metric helps the camera to choose the optimal defocus settings. An optimal Wiener filter then recovers the captured scene and yields sharper images with reduced aliasing. The numerical and visual results show that our method is superior to current acquisition methods used by most digital cameras.

A NEW METHOD FOR ESTIMATING THE 3D SIZE-DISTRIBUTIONCURVE OF FRAGMENTED ROCKS OUT OF 2D IMAGES

Image analysis of rock fragmentation is used in mines and quarries to control the quality of blasting. Obtained information is the particle-size-distribution curve relating volume-proportions to the sizes of fragments. Calculation by image analysis of this particle-size-distribution is carried out in several steps, and each step has its inherent limitations. We will focus in this paper on one of themost crucial steps: reconstructing the volumes (3D). For the 3D-step, we have noticed that, due to the current acquisition method, there is no correlation between the average grey level of surfaces of the fragments and their third dimension. Consequently volumes (3D) as well as the sizes (1D) has to be calculated indirectly from the extracted projected areas of the visible fragments of images. For this purpose, we have built in laboratory a set of images of fragmented rocks resulting from blasting. Moreover, several tests based on comparisons between image analysis and screening measurements were carried out. A new stereological method, based on the comparison of the densities of probability (histograms) of the samemeasurements (with very weak covering and overlapping)was elaborated. It allows us to estimate correctly, for a given type of rock, two intrinsic laws weighing the projected areas distribution in order to predict the volumic distribution.

Quality and matching performance analysis of three-dimensional unraveled fingerprints

The use of fingerprints as a biometric is both the oldest mode of computer-aided personal identification and the most-relied-on technology in use today. However, current acquisition methods have some challenging and peculiar difficulties. For higher performance fingerprint data acquisition and verification, a novel noncontact 3-D fingerprint scanner is investigated, where both the detailed 3-D and albedo information of the finger is obtained. The obtained high-resolution 3-D prints are further converted into 3-D unraveled prints, to be compatible with traditional 2-D automatic fingerprint identification systems. As a result, many limitations imposed on conventional fingerprint capture and processing can be reduced by the unobtrusiveness of this approach and the extra depth information acquired. To compare the quality and matching performances of 3-D unraveled with traditional 2-D plain fingerprints, we collect both 3-D prints and their 2-D plain counterparts. The print quality and matching performances are evaluated and analyzed by using National Institute of Standard Technology fingerprint software. Experimental results show that the 3-D unraveled print outperforms the 2-D print in both quality and matching performances.

Analysis of Artifacts in Four-dimensional CT Images of 50 Abdominal and Thoracic Radiotherapy Patients

It has been recognized that four-dimensional (4D) CT is useful to account for respiratory motion in the treatment planning. Even with 4D-CT imaging, the current acquisition methods can still lead to artifacts. The purpose of this study was to quantify the type, frequency and magnitude of artifacts in 4D-CT images acquired using a multislice cine method. Fifty patients, who underwent 4D-CT scanning and radiotherapy for thoracic or abdominal cancers, were included in this study. All the 4D-CT scans were performed on the GE multislice PET/CT scanner with the Varian RPM system in cine mode. The GE Advantage 4D software was used to create 4D-CT data sets. The artifacts were then visually and quantitatively analyzed by reviewing the images at different positions and respiratory phases. We determined the four types of artifacts: blurring, duplicate structure, overlapping structure, and incomplete structure. All the artifacts observed in this study were classified into one of these four types. The magnitude of each artifact was evaluated by measuring the distance in the superior-inferior direction between the edge of the artifact and the “true” edge of the organ. We further performed statistical analyses to evaluate the relationships between patient- or breathing pattern-related parameters and the occurrence as well as magnitude of artifacts. It was found that 46 of 50 patients (92%) had at least one artifact with a mean magnitude of 11.6 mm (range, 4.4 - 56.0 mm) in the diaphragm or heart. We also observed at least one artifact in 6 of 20 lung or mediastinal tumors (30%). Statistical analysis revealed that there were significant differences between several breathing pattern-related parameters, including abdominal displacement (p < 0.0001), respiratory period (p < 0.0001) and respiratory irregularity (p = 0.0236), for the subgroups of patients with and without artifacts. The magnitude of an artifact in the diaphragm was found to be significantly correlated with the abdominal displacement difference between two adjacent couch positions (R = 0.3383, p = 0.0039). This study has identified that the frequency and magnitude of artifacts in 4D-CT is alarmingly high (over 90%). This high value is of particular concern as the true number of artifacts is probably higher than that given by the current method. Significant improvement is needed in 4D-CT imaging, through either breathing training, improved acquisition methods during scanning, or post-scan image processing.

Dualband spectral-spatial RF pulses for prostate MR spectroscopic imaging.

Although MR spectroscopic imaging (MRSI) of the prostate has demonstrated clinical utility for the staging and monitoring of cancer extent, current acquisition methods are often inadequate in several aspects. Conventional 180 degrees pulses can suffer from chemical shift misregistration, and have high peak-power requirements that can exceed hardware limits in many prostate MRSI studies. Optimal water and lipid suppression are also critical to obtain interpretable spectra. While complete suppression of the periprostatic lipid resonance is desired, controlled partial suppression of water can provide a valuable phase and frequency reference for data analysis and an assessment of experimental success in cases in which all other resonances are undetectable following treatment. In this study, new spectral-spatial RF pulses were developed to negate chemical shift misregistration errors and to provide dualband excitation with partial excitation of the water resonance and full excitation of the metabolites of interest. Optimal phase modulation was also included in the pulse design to provide 40% reduction in peak RF power. Patient studies using the new pulses demonstrated both feasibility and clear benefits in the reliability and applicability of prostate cancer MRSI.

Rapid Three-Dimensional Myocardial Contrast Echocardiography: Volumetric Quantitation of Nonperfused Myocardium After Intravenous Contrast Administration.

Current acquisition methods for quantitative three-dimensional myocardial contrast echocardiography require long acquisition times and therefore require the invasive administration of deposit contrast agents administered intra-arterially or into the left atrium. This study addressed the feasibility of obtaining accurate and precise quantitative volumetric measurements of nonperfused myocardium after an intravenous bolus of echocardiographic contrast agent using a rapid three-dimensional myocardial contrast echocardiographic acquisition technique. An open-chest pig model of acute left anterior descending coronary artery (LAD) occlusion was used. After LAD ligature, an intravenous bolus of contrast agent was given and images were obtained over a 12-second period using a continuously rotating transducer placed at the apical position. There was no significant microbubble destruction during the rotational acquisition period as measured by differences in mean gray scale values of apical, mid, and basal myocardial regions between the first and last image frames of acquisition. Calculated volumes of nonperfused myocardium demonstrated significant agreement and correlation (mean difference +/- SD = -0.30 +/- 1.71 cm(3); r = 0.89; P < 0.01; y = 1.06x - 1.08) with anatomic specimens. When expressed as percent of total LV volume being nonperfused, the mean difference +/- SD was 2.1 +/- 3.6%, r = 0.94, P < 0.01, and y = 1.33x - 4.08. We conclude that accurate and precise measurements of nonperfused myocardium after an acute LAD coronary artery occlusion can be obtained after the intravenous bolus administration of a contrast material when a rapid 12-second acquisition with a continuously rotating transducer is used.