Heart rate estimation from color video sequences with high SNR.

We propose an absorption intensity heartbeat modulation-averaged shifted histogram (AIHM-ASH) method for estimating human heart rate (HR) using color videos of lip image sequences. When heartbeat occurs, AIHM is generated. Based on the AIHM, HR signals can be demodulated by computing the instantaneous HR modulation depth that presents the relative red blood cell (RBC) concentration from the green channel image of the RGB color video. In addition, the ASH algorithm further suppresses the background tissue and vein signals, and increases the signal-to-noise ratio (SNR). The experimental results for flow phantoms, chicken embryos, and human lips validated the proposed method's optimal estimation conditions and effectiveness, where the accuracy and root mean square error (RMSE) were 99.23% and 0.8 bpm, respectively. The proposed HR estimation method has significant potential to advance health monitoring and disease prevention via conventional color video cameras installed in public places.

Tri-zone flame spatial structure imaging combined with endogenic polarized scattering.

We propose a multi-mode optical imaging method to retrieve the 2D and 3D spatial structures of the preheating, reaction, and recombination zones of an axisymmetric steady flame. In the proposed method, an infrared camera, a visible light monochromatic camera, and a polarization camera are triggered synchronously to capture 2D flame images, and their corresponding 3D images are reconstructed by combining different projection position images. The results of the experiments conducted indicate that the infrared and visible light images represent the flame preheating and flame reaction zones, respectively. The polarized image can be obtained by computing the degree of linear polarization (DOLP) of raw images captured by the polarization camera. We discover that the highlighted regions in the DOLP images lie outside the infrared and visible light zones; they are insensitive to the flame reaction and have different spatial structures for different fuels. We deduce that the combustion product particles cause endogenic polarized scattering, and that the DOLP images represent the flame recombination zone. This study focuses on the combustion mechanisms, such as the formation of combustion products and quantitative flame composition and structure.

Phytochemical composition profile and space-time accumulation of secondary metabolites for Dracocephalum moldavica Linn. via UPLC-Q/TOF-MS and HPLC-DAD method.

The aerial parts of Dracocephalum moldavica L. are extensively used in traditional ethnic medicines in China as a remedy for cardiovascular and cerebrovascular damage. However, the chemical composition and the accumulation of main secondary metabolites of D. moldavica in different natural environments remain unclear. This study aimed to conduct a qualitative and quantitative analysis of the main secondary metabolites to explore the quality variation of D. moldavica in markets. The evaluation of space-time accumulation of main secondary metabolites in D. moldavica was carried out during different growth periods and in different geographical locations. A total of 35 ingredients were detected and 24 identified, including 21 flavonoids, two phenolic acids and one coumarin by UPLC-QTOF-MS method. Furthermore, a simple and convenient HPLC method was successfully developed for the simultaneous determination of lutelin-7-O-glucuronide and tilianin and rosmarinic acid in D. moldavica. The results of space-time accumulation analysis showed the distinct variation of secondary metabolites of D. moldavica with the growth period and geographical location. Finally, the current study provided a meaningful and useful approach for comprehensively evaluating the quality of D. moldavica.

Simultaneous determination of polyphenols and triterpenes in pomegranate peel based on high-performance liquid chromatography fingerprint by solvent extraction and ratio blending method in tandem with wavelength switching.

Traditionally, pomegranate (Punica granatum L.) has been consumed as fresh fruit or as pomegranate juice. Pomegranate peel, the dried husk of P· granatum, is an important herbal medicine for treating diarrhea, hemostasis and insect-induced abdominal pain in China. However, the quality control methods for pomegranate peel remain unsatisfactory. In this work, a new HPLC-based qualitative and quantitative method for quality control of pomegranate peel was developed and validated for the simultaneous determination of polyphenols and triterpenes (including punicalagins A and B, ellagic acid, oleanolic acid and ursolic acid) by solvent extraction and ratio blending method in tandem with wavelength switching. The average recoveries were 98.07-100.61% with relative standard deviation no more than 4.27%. In addition, the fingerprint analysis was conducted to interpret the consistency of the quality test. Thirteen characteristic peaks were selected to evaluate the similarities of 16 batches of pomegranate peel. The similarities of samples were all more than 0.80, indicating that the samples from different areas of China were consistent. The results demonstrated that quantitative analysis and the HPLC fingerprint as a characteristic distinguishing method combining similarity evaluation can be successfully used to assess the quality and to identify the authenticity of pomegranate peel.

Potential Pharmacokinetic Drug⁻Drug Interaction Between Harmine, a Cholinesterase Inhibitor, and Memantine, a Non-Competitive N-Methyl-d-Aspartate Receptor Antagonist.

Harmine (HAR) is a beta-carboline alkaloid widely distributed in nature. It exhibits psychopharmacological effects of improving learning and memory. However, excessive dose of HAR can cause central tremor toxicity, which may be related to the glutamate system. Memantine (MEM) is a non-competitive N-methyl-d-aspartate receptor antagonist. It can be used for the treatment of Alzheimer's disease and also can block the neurotoxicity caused by glutamate. Therefore, combination of HAR and MEM would be meaningful and the pharmacokinetics investigation of HAR and MEM in combination is necessary. A ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was established and validated for the simultaneous quantitative determination of MEM, HAR and harmol (HOL), a main metabolite of HAR, in rat plasma after oral administration of HAR and MEM in combination (5.0 mg/kg of MEM combined with 20.0, 40.0, 80.0 mg/kg of HAR). The contents of HAR and HOL were determined after oral administration of HAR (20.0, 40.0 and 80.0 mg/kg), and the content of MEM was determined after oral administration of MEM (5.0 mg/kg). Blood samples were collected from each rat at 0 (pre-dose), 0.08, 0.17, 0.25, 0.33, 0.50, 0.75, 1.0, 2.0, 4.0, 8.0, 12.0 and 24.0 h after administration. The maximum peak concentration (Cmax) of MEM was obviously decreased, and the area under the plasma concentration versus time curve from zero to time t (AUC(0-t)) and mean residence time (MRT) were significantly increased after combination with HAR. The Cmax and AUC(0-t) of HAR and its metabolite HOL were increased after combination with MEM. These findings suggested that co-administration of HAR and MEM could extend their residence time in rats, and then might increase the efficacy for treatment of Alzheimer's disease. Therefore, this study will provide a basis for the rational combined application of HAR and MEM.

Establishment and application of a new HPLC qualitative and quantitative assay for Gentiana Macrophyllae Radix based on characteristic constituents of anofinic acid and its derivatives.

Gentiana Macrophylla Radix (GMR) is officially used as traditional Chinese medicine, but easily confused with Gentianae Radix et Rhizoma (GRR) and adulterants. This study aimed to establish an HPLC method for qualitative and quantitative analysis of GMR based on characteristic components, anofinic acid and its derivatives. HPLC analysis was performed on a C18 column with gradient elution using acetonitrile and 0.1% phosphoric acid as mobile phase, and detected at 240 nm by conventional methodology validation. For fingerprint analysis, RSDs of relative retention times and relative peak areas of the characteristic peaks were within 0-1.10 and 0-4.08%, respectively. For determination of 2-methoxyanofinic acid, the calibration curve showed good linearity (R2 > 0.9999) within the test range. The RSDs of precision, repeatability and stability test did not exceed 2.46, 0.83 and 1.11%, respectively. The average recoveries were between 95.08 and 103.05% with RSDs ≤2.29%. The results showed that there was no significant difference among the four species of GMR, but there were significant differences among GMR, GRR and spurious breeds by principal component analysis and hierarchical cluster analysis. Anofinic acid and its derivatives, as the characteristic markers, could be used for the identification and quality control of GMR.

Targeted Fe-filled carbon nanotube as a multifunctional contrast agent for thermoacoustic and magnetic resonance imaging of tumor in living mice.

Microwave-induced thermoacoustic imaging (TAI) can map the microwave absorption distribution of targets, which depends on the electrical and magnetic properties. Although carbon nanotubes (CNTs) with good electrical properties have been used as TAI contrast agents, the negligible magnetic absorption hinders its application for sensitive detection. In order to exploit CNTs with electrical and magnetic absorption properties as agent of TAI, the ferromagnetic material-filled multi-walled CNTs (MMWCNTs) are investigated. In this study, the folic acid conjugated plain multiwalled CNTs (MWCNTs) and MMWCNTs were injected through the tail-vein of mice separately, and TAI and magnetic resonance imaging (MRI) were performed. The results show the MMWCNTs can clearly image the size and edge of the tumor with the TAI contrast enhancement of 67% and T2 signal intensity decrease of four fifths compared to MWCNTs. This study demonstrated the hybrid particles have the potential to be a high-sensitive contrast agent for accurate tumor detection. From the Clinical Editor: Novel imaging modalities are emerging. Microwave-induced thermoacoustic imaging (TAI) relies on the absorption distribution of microwave of targets. In this article the authors investigate the use of ferromagnetic material-filled multi-walled CNTs as contrast agents for both TAI and MRI in an in-vivo model for tumors. The positive findings would imply that the application of dual-modality probe could provide more accurate imaging for the clinical setting.

Handheld Thermoacoustic Scanning System Based on a Linear-array Transducer.

To receive the information necessary for imaging, traditional microwave-induced thermoacoustic imaging systems (MITISs) use a type of circular-scanning mode using single or arc detectors. However, the use of MITISs for body scanning is complicated by restrictions in space and imaging time. A linear-array detector, the most widely used transducer in medical ultrasound imaging systems for body scanning, is a possible alternative to MITISs for scanning biological tissues, such as from the breast or limbs. In this paper, a handheld MITIS, based on a linear-array detector and a multiple data acquisition system, is described, and the capacity of the system is explored experimentally. First, the vertical and lateral resolution of the system is discussed. Next, real-time imaging of a moving object, obtained with an image capture rate of 20 frame/s, is described. Finally, a phantom experiment is detailed, investigating the overall imaging capability. The results show that this system achieves rapid scanning with a large field of view. The system has the obvious advantages of being handheld, not using coupled fluids, and achieving real-time imaging with a large field of view, which make this MITIS more suitable for clinical applications.

Choroidal vascularity index (CVI)-Net-based automatic assessment of diabetic retinopathy severity using CVI in optical coherence tomography images.

A deep learning model called choroidal vascularity index (CVI)-Net is proposed to automatically segment the choroid layer and its vessels in overall optical coherence tomography (OCT) scans. Clinical parameters are then automatically quantified to determine structural and vascular changes in the choroid with the progression of diabetic retinopathy (DR) severity. The study includes 65 eyes consisting of 34 with proliferative DR (PDR), 17 with nonproliferative DR (NPDR), and 14 healthy controls from two OCT systems. On a dataset of 396 OCT B-scan images with manually annotated ground truths, overall Dice coefficients of 96.6 ± 1.5 and 89.1 ± 3.1 are obtained by CVI-Net for the choroid layer and vessel segmentation, respectively. The mean CVI values among the normal, NPDR, and PDR groups are consistent with reported outcomes. Statistical results indicate that CVI shows a significant negative correlation with DR severity level, and this correlation is independent of changes in other physiological parameters.

Probing Individual Particles in Aquatic Suspensions by Simultaneously Measuring Polarized Light Scattering and Fluorescence.

Suspended particles play a significant role in aquatic systems. However, existing methods to probe suspended particles have several limitations. In this paper, we present a portable prototype to in situ probe individual particles in aquatic suspensions by simultaneously measuring polarized light scattering and fluorescence, aiming to obtain an effective classification of microplastics and microalgae. Results show that the obtained classification accuracy is significantly higher than that for either of these two methods. The setup also successfully measures submicron particles and discriminates two species of Synechococcus. Our study demonstrates the feasibility of simultaneously measuring polarized light scattering and fluorescence, and the promising capability of our method for further aquatic environmental monitoring.