Non-invasive Measurement Method Research Articles

Validation of oscillometric ratio and maximum gradient methods for non-invasive blood pressure measurement with intra-arterial blood pressure measurements as reference.

Most non-invasive blood pressure (BP) measurements are carried out using instruments which implement either the Ratio or the Maximum Gradient oscillometric method, mostly during cuff deflation, but more rarely during cuff inflation. Yet, there is little published literature on the relative advantages and accuracy of these two methods. In this study of 40 lightly sedated individuals aged 64.1 ± 9.6 years, we evaluate and compare the performance of the oscillometric ratio (K) and gradient (Grad) methods for the non-invasive estimation of mean pressure, SBP and DBP with reference to invasive intra-arterial values. There was no significant difference between intra-arterial estimates of mean pressure made via Korotkoff sounds (MP-OWE) or the gradient method (MP-Grad). However, 17.7% of MP-OWE and 15% of MP-Grad were in error by more than 10 mmHg. SBP-K and SBP-Grad underestimated SBP by 14 and 18 mmHg, whilst accurately estimating DBP with mean errors of 0.4 ± 5.0 and 1.7 ± 6.1 mmHg, respectively. Relative to the reference standard SBP-K, SBP-Grad and DBP-Grad were estimated with a mean error of -4.5 ± 6.6 and 1.4 ± 5.6 mmHg, respectively, noting that using the full range of recommended ratios introduces errors of 12 and 7 mmHg in SBP and DBP, respectively. We also show that it is possible to find ratios which minimize the root mean square error (RMSE) and the mean error for any particular individual cohort. We developed linear models for estimating SBP and SBP-K from a range of demographic and non-invasive OWE variables with resulting mean errors of 0.15 ± 5.6 and 0.3 ± 5.7 mmHg, acceptable according to the Universal standard.

Non-invasive measurement of rat auditory evoked fields using an optically pumped atomic magnetometer: Effects of task manipulation

Optically pumped magnetometers (OPMs) have become a favorable tool for magnetoencephalography (MEG) measurement, offering a non-invasive method of measurement. OPMs do not require cryogenic environments, sensors can be more closely aligned with the brain. We employed a passive single-stimulus paradigm in conjunction with OPMs with a sensitivity of 20 fT/ Hz to investigate the auditory response of rats to inter-stimulus interval (ISI) and frequencies, recording the rat auditory event-related magnetic fields (ERMFs). Our findings include: (1) Auditory evoked fields can be detected non-invasively by OPMs; (2) The amplitude of the rat auditory ERMFs varies with changes in ISI, with more pronounced amplitude changes observed after 5 s; (3) When the sound stimulus frequency is altered at the same ISI, the amplitude of the rats ERMFs changes with frequency, indicating significant differences in attention. Our method offers a valuable tool for the clinical application of a single stimulus paradigm and opens up a new avenue for research on the brain magnetic field detections.

The Influence of Models of Different Structures of Strength Training Classes in Horting on the Indicators of Bioimpedansometry

Topicality. In the modern system of training in mixed martial arts, in particular in the sport of horticulture, the search for optimal models of training programs aimed at improving strength capabilities and body composition of athletes is actively investigated. The Purpose of the Research. To study the peculiarities of the influence of different models of strength training in horting on the indicators of the body composition of athletes.. Methods. 60 athletes who have been involved in horting for 3–4 years took part in the study. 3 research groups were formed. The representatives of the examined groups used experimental training models during 3 months of strength training. Using the non-invasive method of bioimpedance measurement during all stages of the study, the nature of changes in parameters of body composition indicators was assessed. The Results. It was established that only representatives of the 2nd group showed a positive increase in parameters of active cellular body mass (ACM, %) by 3,7 % (p<0,05) during the 3 months of the study compared to the initial data. A significant decrease in the parameters of this body composition indicator was found in the athletes of the other two groups. The greatest increase in BJM among the participants was found in athletes of group 3. At the same time, in representatives of group 1, the level of the studied indicator is almost half as low as compared to the results that were found in athletes of group 3 during the three months of the experiment. The greatest dynamics towards a decrease in the BM indicator (%) by 2,8 % (p<0,05), over the entire period of the study, is observed in athletes of group 1. At the same time, in the representatives of the other two groups, during the entire period of the experiment, we observe identical dynamics of the investigated body composition indicator, the level of which differs by only 0,7 % from the results demonstrated by the athletes of the 1st group. Findings. The use in the process of strength training in horting of variations of exercise complexes effective in strength fitness on simulators under the conditions of the principle of “premature fatigue” of agonist muscles due to exercises of an isolating nature, allows to maximally influence the parameters of body composition compared to the results that were found in other conditions of training activities.

Deletion of Sigmar1 leads to increased arterial stiffness and altered mitochondrial respiration resulting in vascular dysfunction.

Sigmar1 is a ubiquitously expressed, multifunctional protein known for its cardioprotective roles in cardiovascular diseases. While accumulating evidence indicate a critical role of Sigmar1 in cardiac biology, its physiological function in the vasculature remains unknown. In this study, we characterized the expression of Sigmar1 in the vascular wall and assessed its physiological function in the vascular system using global Sigmar1 knockout (Sigmar1-/-) mice. We determined the expression of Sigmar1 in the vascular tissue using immunostaining and biochemical experiments in both human and mouse blood vessels. Deletion of Sigmar1 globally in mice (Sigmar1-/-) led to blood vessel wall reorganizations characterized by nuclei disarray of vascular smooth muscle cells, altered organizations of elastic lamina, and higher collagen fibers deposition in and around the arteries compared to wildtype littermate controls (Wt). Vascular function was assessed in mice using non-invasive time-transit method of aortic stiffness measurement and flow-mediated dilation (FMD) of the left femoral artery. Sigmar1-/- mice showed a notable increase in arterial stiffness in the abdominal aorta and failed to increase the vessel diameter in response to reactive-hyperemia compared to Wt. This was consistent with reduced plasma and tissue nitric-oxide bioavailability (NOx) and decreased phosphorylation of endothelial nitric oxide synthase (eNOS) in the aorta of Sigmar1-/- mice. Ultrastructural analysis by transmission electron microscopy (TEM) of aorta sections showed accumulation of elongated shaped mitochondria in both vascular smooth muscle and endothelial cells of Sigmar1-/- mice. In accordance, decreased mitochondrial respirometry parameters were found in ex-vivo aortic rings from Sigmar1 deficient mice compared to Wt controls. These data indicate a potential role of Sigmar1 in maintaining vascular homeostasis.

Numerical investigation of crack propagation regimes in snow fracture experiments

A snow slab avalanche releases after failure initiation and crack propagation in a highly porous weak snow layer buried below a cohesive slab. While our knowledge of crack propagation during avalanche formation has greatly improved over the last decades, it still remains unclear how snow mechanical properties affect the dynamics of crack propagation. This is partly due to a lack of non-invasive measurement methods to investigate the micro-mechanical aspects of the process. Using a DEM model, we therefore analyzed the influence of snow cover properties on the dynamics of crack propagation in weak snowpack layers. By focusing on the steady-state crack speed, our results showed two distinct fracture process regimes that depend on slope angle, leading to very different crack propagation speeds. For long experiments on level terrain, weak layer fracture is mainly driven by compressive stresses. Steady-state crack speed mainly depends on slab and weak layer elastic moduli as well as weak layer strength. We suggest a semi-empirical model to predict crack speed, which can be up to 0.6 times the slab shear wave speed. For long experiments on steep slopes, a supershear regime appeared, where the crack propagation speed reached approximately 1.6 times the slab shear wave speed. A detailed micro-mechanical analysis of stresses revealed a fracture principally driven by shear. Overall, our findings provide new insight into the micro-mechanics of dynamic crack propagation in snow, and how these are linked to snow cover properties.Graphical

Measurement of cryogenic valve straightness without accessing valve exterior

The work presents a method of noninvasive measurement of long-stem cryogenic valve straightness, using simple and generally available means. The method does not require an access to valve exterior, what is a common requirement in practice, where such access is impossible in case of helium cryogenic valves confined in all-welded valve boxes. Valve’s deflection is computed using computer vision algorithms (Hough transform for circles), based on photographs of valve interior. Results obtained by the method have been validated using reference data from a validation test stand with a ruler for deflection measurement. The method may be applied for a more general case, namely to measure deflections of pipes ended with sleeves with diameters smaller than the pipe’s diameter.

Air gap flux density measurement of PMSLM based on TMR sensing external stray magnetic field and CNN-LSTM

This paper presents a new non-invasive air gap flux density measurement method for permanent magnet synchronous linear motor (PMSLM) using tunneling magnetoresistance (TMR) sensor and convolutional neural networks-long short-term memory (CNN-LSTM) regression modeling. First, the analytical and finite element models of the air gap magnetic field of PMSLM are established as the data basis. Second, TMR sensor is used to measure the external stray magnetic density. Gramian Angular Field method combined with image similarity matching technology are used to obtain the optimal measurement position of the TMR sensor. Then, a new deep learning regression method as CNN-LSTM is introduced to establish a high-precision mapping model to realize non-invasive high-precision measurement of the air gap magnetic density by “substituting external to internal.” Finally, PMSLM prototype experimental platform with TMR sensor hardware acquisition circuit is built. Comparison confirmatory experiments with Gauss meter can verify the effectiveness and superiority of the proposed method.

ACNN-BiLSTM: A Deep Learning Approach for Continuous Noninvasive Blood Pressure Measurement Using Multi-Wavelength PPG Fusion.

As an essential physiological indicator within the human body, noninvasive continuous blood pressure (BP) measurement is critical in the prevention and treatment of cardiovascular disease. However, traditional methods of blood pressure prediction using a single-wavelength Photoplethysmographic (PPG) have bottlenecks in further improving BP prediction accuracy, which limits their development in clinical application and dissemination. To this end, this study proposed a method to fuse a four-wavelength PPG and a BP prediction model based on the attention mechanism of a convolutional neural network and bidirectional long- and short-term memory (ACNN-BiLSTM). The effectiveness of a multi-wavelength PPG fusion method for blood pressure prediction was evaluated by processing PPG signals from 162 volunteers. The study compared the performance of the PPG signals with different individual wavelengths and using a multi-wavelength PPG fusion method in blood pressure prediction, assessed using mean absolute error (MAE), root mean squared error (RMSE) and AAMI-related criteria. The experimental results showed that the ACNN-BiLSTM model achieved a better MAE ± RMSE for a systolic BP and diastolic BP of 1.67 ± 5.28 and 1.15 ± 2.53 mmHg, respectively, when using the multi-wavelength PPG fusion method. As a result, the ACNN-BiLSTM blood pressure model based on multi-wavelength PPG fusion could be considered a promising method for noninvasive continuous BP measurement.

Evaluation of the oscillometric method for noninvasive blood pressure measurement during cuff deflation and cuff inflation with reference to intra-arterial blood pressure.

There is little quantitative clinical data available to support blood pressure measurement accuracy during cuff inflation. In this study of 35 male and 5 female lightly anaesthetized subjects aged 64.1 ± 9.6 years, we evaluate and compare the performance of both the oscillometric ratio and gradient methods during cuff deflation and cuff inflation with reference to intra-arterial measurements. We show that the oscillometric waveform envelopes (OWE), which are key to both methods, exhibit significant variability in both shape and smoothness leading to at least 15% error in the determination of mean pressure (MP). We confirm the observation from our previous studies that K1 Korotkoff sounds underestimate systolic blood pressure (SBP) and note that this underestimation is increased during cuff inflation. The estimation of diastolic blood pressure (DBP) is generally accurate for both the ratio and the gradient method, with the latter showing a significant increase during inflation. Since the gradient method estimates SBP and DBP from points of maximum gradient on each OWE recorded, it may offer significant benefits over the ratio method. However, we have shown that the ratio method can be optimized for any data set to achieve either a minimum mean error (ME) of close to 0 mmHg or minimum root mean square error (RMSE) with standard deviation (SD) of <5.0 mmHg. We conclude that whilst cuff inflation may offer some advantages, these are neither significant nor substantial, leaving as the only benefit, the potential for more rapid measurement and less patient discomfort.

Development of long-range conductivity mechanisms in glass-like carbon

The conductivity mechanisms in glass-like carbon synthesised from SU-8 3005 photoresist are explored as a function of pyrolysis temperature (between 700–750 °C) utilising microwave dielectric spectroscopy techniques. Broadband measurements using an open-ended coaxial probe (BCP) are used to investigate the complex permittivity and conductivity as a function of frequency and show the development of long range conduction and sp2 carbon chain formation. Fixed frequency resonance measurements using microwave cavity perturbation (MCP) methods are shown as a way of measuring this transition and change in Q-factor without requiring contacts and therefore acting as a effective method for non-destructive and non-invasive measurements. Using these methods we show a clear change in the AC conductivity of glass-like carbon at a pyrolysis temperature of ∼730 °C and demonstrate how microwave cavity perturbation (MCP) can be used as a non-contact method of dielectric spectroscopy for determining the transition of conductivity mechanisms in glass-like carbon from short to long range and therefore as a method for non-destructive material quality control. We demonstrate that both BCP and MCP dielectric spectroscopy methods are effective at clearly detecting changes in the structure and conductivity mechanisms of glass-like carbon over a small pyrolysis temperature range.

Measurement the 3D temperature distribution in the combustion zone using acoustic tomography and nolinear wavefont tracing

A non-invasive temperature measurement method in three dimensions is proposed to reconstruct the three-dimensional temperature. It relies on the use of nonlinear acoustic travel-time tomography, which incorporates acoustic path tracing, Gaussian kernel function, and modified Tikhonov regularization. Sound signals can be distorted due to large average temperature gradients and oscillatory release of heat in the combustion region. The effective acoustic signal is extracted based on spectral subtraction to evaluate the sound propagation time under distorted signals. The analysis of experimental errors indicates that the proposed acoustic pyrometry method has an average relative error of less than 15% compared to the time-averaged temperature measured by thermocouples. This result verifies the efficacy of the method when it comes to accurately reconstructing the temperature field in the combustion area. The reduction in error is attributed to the consideration of acoustic ray tracing within the proposed method.

The Relationship between Lumbar Puncture Opening Pressure and Retinal Nerve Fiber Layer Thickness in the Diagnosis of Idiopathic Intracranial Hypertension: Is a Lumbar Puncture Always Necessary?

Idiopathic intracranial hypertension (IIH), is characterized by elevated intracranial pressure (ICP) without an identified cause. Today, lumbar puncture (LP) is the most common method used for diagnosis by measuring cerebrospinal fluid (CSF) pressure to reflect intracranial pressure. This invasive examination has significant disadvantages, such as complications and negative experiences for patients. Therefore, noninvasive methods for ICP measurement are desired. Optical coherence tomography (OCT) is widely used for the diagnosis and follow-up of IIH patients as it reflects papilledema. The aim of this study is to investigate the relationship between CSF pressure and OCT parameters and the ability of OCT in the diagnostic approach. In our study, patients who were followed up with a diagnosis of IIH with complete neuro-ophthalmological examinations, including visual acuity (VA), visual field, and OCT imaging within 24 hours before lumbar puncture, were retrospectively evaluated. CSF pressure, visual acuity LogMAR, mean deviation of visual fields, retinal nerve fiber layer (RNFL) thickness measured by OCT, and treatment protocols were obtained from our hospital data system. A total of 42 eyes of 21 patients were enrolled in the study. A statistically significant positive and moderate correlation was found between CSF pressure values and average RNFL thickness (r=0.507; P=0.001). The same relationship was demonstrated in all 4 quadrants: inferior, superior, nasal, and temporal. Increased peripapillary RNFL thickness in optic nerve head OCT may be correlated with increased ICP in IIH patients. A larger number of patients are needed to better understand the correlation between OCT parameters and CSF pressure in patients with IIH.

Comparative Analysis of Non-Invasive Measurement Methods for Optimizing Architectural Documentation

Architectural documentation not only plays a critical role in the conservation of historical structures, but also enables their detailed comprehension of the structure. This study aims to assess the most effective methods for drawing and modeling architectural structures and present their advantages and disadvantages. Measurements play a significant role in this context, and today's technology offers the potential to accelerate this process and enhance accuracy. However, the application of these technologies can impose additional burdens such as elevated expenses, the requisite for specialized personnel, and the management of substantial data volumes. Therefore, determining the appropriate measurement method in line with the quality of architectural documentation is essential. For this study, the Mosque of Kurşunlu Complex in Eskişehir was selected for its historical and topographical attributes which enabled all methods to be examined. The data produced via terrestrial laser scanning, aerial photogrammetry and terrestrial photogrammetry methods were examined in terms of the production of drawings and models for different analysis methods such as structure, daylight and building acoustics, as well as survey drawings required for the architectural documentation processes of the building. The study concluded that no single method could produce holistic data on its own, and the best results for comprehensive documentation were achieved by integrating terrestrial laser scanning and aerial photogrammetry. Furthermore, for products that do not require comprehensive data, photogrammetric methods were more efficient.

Innovative non-invasive ultrasound method for whisky cask liquid level measurement

Regular measurement and inspection of whisky casks are crucial for ensuring quality and effective inventory management. This process helps detect issues such as leaks, damage, and contamination that can harm the whisky’s condition. Additionally, monitoring the whisky level provides valuable insights into maturation progress, evaporation rates, and production planning to account for expected losses. Currently, the industry relies on dipsticks and pressure sensors to measure liquid levels in casks. Dipsticks require moving casks from high shelves, risking human safety, the utilisation of extensive resources and necessitating cask opening, which has inherent issues. Pressure sensors, installed inside casks, are sensitive to temperature, limiting their accuracy and suitability for warehouse testing. This paper presents a new non-invasive method using ultrasound to measure liquid levels in wooden casks. An external ultrasonic probe glides along the surface of the cask. By leveraging the distinct ultrasonic acoustic properties in the liquid and the air, the sensor can detect the upper boundary of the liquid, thereby indicating the whisky level. Since this new method only needs to access a small portion of the cask to measure the level, it enables distilleries to accurately monitor cask contents on-site, reducing the costs and risks associated with moving casks. The paper also includes quantitative data on ultrasonic properties such as moisture, velocity, and signal attenuation for various cask samples. The prototype system successfully demonstrated this approach on a retired Ex-Bourbon whisky cask, providing precise liquid level measurements on different surfaces and storage orientations without the need for cask opening. It achieved centimetre-level accuracy compared to dipstick reference readings.

Non-invasive methods for heart rate measurement in fish based on photoplethysmography.

Heart rate is a crucial physiological indicator for fish, but current measurement methods are often invasive or require delicate manipulation. In this study, we introduced two non-invasive and easy-to-operate methods based on photoplethysmography, namely reflectance type photoplethysmography (PPG) and remote photoplethysmography (rPPG), which we applied to the large yellow croaker (Larimichthys crocea). PPG showed perfect synchronization with electrocardiogram (ECG), with a Pearson's correlation coefficient of 0.99999. For rPPG, the results showed good agreement with ECG. Under active provision of green light, the Pearson's correlation coefficient was 0.966, surpassing the value of 0.947 under natural light. Additionally, the Root Mean Square Error was 0.810, which was lower than the value of 1.30 under natural light, indicating that the rPPG method not only had relatively high accuracy, but also that green light may have the potential to further improve its accuracy.

Features extraction from cardiac-related signals: comparison among different measurement methods

Heart Rate (HR), Heart Rate Variability (HRV), and cardiac time intervals are clinically relevant parameters, which can be assessed from the analysis of electrocardiogram (ECG). Some aspects of cardiac activity can be investigated also by means of different noninvasive and non-intrusive measurement methods, such as phonocardiograph (PCG), photoplethysmograph (PPG), and vibrocardiograph (VCG). However, the standard processing algorithms (i.e., Pan & Tompkins) do not allow to fully characterize waveforms different from ECG. In the past, some of the authors have already demonstrated the efficiency of a novel processing procedure for the precise HR measurement from the above-mentioned signals. In the present work, data processing procedure has been improved and deeply extended to assess HRV parameters and time intervals from all the signals acquired on an extended experimental campaign, involving 26 subjects, on whom ECG, PPG, PCG, and VCG signals were simultaneously measured. Results prove that this approach can overcome the drawbacks of standard algorithms and can be widely applied to signals of different nature to derive HR, HRV, and time intervals. As regards HR measurement, PPG proved to be the most accurate measurement method (±1.2 bpm), followed by VCG (±1.6 bpm) and PCG (±2.5 bpm). For HRV analysis in the time domain, the use of the proposed methodology allows to obtain clinically relevant parameters statistically comparable to the ECG ones. Finally, the measurement of QT interval by applying personal calibration lines allows to obtain results comparable to the gold standard technique, i.e., ECG (maximum percentage deviation reduced from 10.9% up to <4.3% in VCG).

Pore structure dynamic evolution of coal during hydraulic intrusion based on NMR

Low-field nuclear magnetic resonance (LF-NMR) technology is a non-invasive measurement method, that provides a fast, direct, and nondestructive tool for characterizing complex pore structure. To reveal the evolution law of pore structure and stress sensitivity during hydraulic intrusion, this paper adopts LF-NMR monitoring and in-situ hydraulic intrusion technology to carry out the hydraulic intrusion test on both pre-drilled and un-drilled coal. The quantitatively characterizes the variation patterns of pore structure, compressibility, and other parameters, revealing the dynamic mechanism of pore structure evolution Three dynamic evolution laws of pores were obtained through experimental data analysis. The mechanism of dynamic evolution of pore structure was determined from the perspective of pore compressibility and effective stress. Based on the measurement results, LF-NMR is an efficient non-destructive method for quantifying pore size distributions of the coal.

Quantitative analysis of age-related changes in vascular structure, oxygen saturation, and epidermal melanin structure using photoacoustic methods.

Vascular structure, blood oxygen saturation, and melanin status of the epidermis are chromophore factors related to light absorption. Therefore, they are likely to be related to skin appearance. Thus, it is important to measure these internal skin features and understand their characteristics. Thus, we aimed to analyze the individual differences and aging changes in the skin by measuring the internal skin characteristics, such as vascular structure, oxygen saturation, and the 3D distribution of melanin in the epidermis, using a noninvasive photoacoustic (PA) measurement method. A PA measurement device was used as a noninvasive measurement method. Eighty Japanese women aged between 20 and 60 years were enrolled. The target area was the buccal region of the face. The blood vessel structure showed a decrease in fine vessels with age, with a stronger tendency observed in the dermis layer, and the volume of blood vessels was larger in the dermis layer than in the dermal-subcutaneous fat boundary layer. Oxygen saturation showed a similar decreasing trend with age in all depths examined. Melanin condition as the torus-like pattern structure tended to increase with age. PA measurements revealed the characteristics of several chromophores, providing a new skin aging mechanism.

Experimental studies of a soft industrial exoskeleton in work-related activity for the evaluation of its operational efficiency

For conducting the experiment under laboratory conditions, a dedicated workplace was designed to simulate the activity of lifting / lowering a 20 kg load to a height of 0.7 m in the “Squat” and “Stoop” styles. To implement this study, the following methods were employed: “motion capture” to assess the mechanics of movements in the lumbar spine; a non-invasive method for measurement of the key biological indicators as a comprehensive assessment of the state of the cardiorespiratory system; electromyography (EMG) as the main method for assessing the bioelectrical activity of muscles; interviewing volunteers (on a 10-point scale) as a method of subjective assessment of their physical condition and performance. A study conducted as part of the work meant to determine the effectiveness and safety of using a soft industrial exoskeleton during work-related activity, including the elimination of the harm from stereotypic work movements, showed a decrease in the activity of the measured muscles when using a soft industrial exoskeleton, which also indicates a decrease in human fatigue that increases the effectiveness of its operation.

Non-Invasive Blood Pressure Tracking of Spontaneous Hypertension Rats Using an Electronic Nose.

Traditional noninvasive blood pressure measurement methods in experimental animals are time consuming and difficult to operate, particularly for large numbers of animals. In this study, the possibility of sensing fecal odor to estimate the blood pressure status of spontaneous hypertension rats (SHRs) was explored with the aim of establishing a new method for non-invasive monitoring of blood pressure. The body weight and blood pressure of SHRs kept increasing with growth, and the odor information monitored using an E-nose varied with the blood pressure status, particularly for sensors S6 and S7. The fecal information was analyzed using principal component analysis, canonical discriminant analysis and multilayer perception neural networks (MLP) to discriminate SHRs from normal ones, with a 100% correct classification rate. For better prediction of blood pressure, the model built using multiple linear regression analysis, partial least squares regression analysis and multilayer perceptron neural network analysis were used, with coefficients of determination (R2) ranging from 0.8036 to 0.9926. Moreover, the best prediction model for blood pressure was established using MLP analysis with an R2&not; higher than 0.91. Thus, changes in blood pressure levels can be tracked non-invasively, and normotension can be distinguished from hypertension or even at different hypertension levels based on the odor information of rat feces, providing a foundation for non-invasive health monitoring. This work might provide potential instructions for functional food research aimed at lowering blood pressure.