Near-infrared spectroscopy (NIRS) has increasingly been used to noninvasively determine hemodynamic concentration change noninvasively by detecting light intensity changes. The effect of scalp hair follicle (SHF) on NIRS quantification is highlighted since its dark pigmentations is a strong absorption source to contaminate the NIRS signal. Here we have incorporated the Monte Carlo modeling for light transport in voxelized media, and visible Chinese human with high precision in depicting three-dimensional human anatomical structures, to study the effect of SHF density on NIRS quantification. The results quantified the strong impact of SHF on NIRS measurements and revealed that the detected light intensity signal decreased by 15%-80% when SHF density varied from 1% to 11.1% at Asian human range. More surprisingly, the hemodynamics-interpreted brain activation could be miscalculated by 11.7%-292.24% linearly with SHF density varied in 1%-11.1%. It is the first time that the effect of SHF on NIRS measurements has been quantitatively evaluated and the dramatic influence of SHF is outlined to be seriously concerned. The finding of the linear correlation between NIRS signal underestimation and the density of scalp hair follicles also indicate a potential calibration method to eliminate the SHF effect on NIRS measurement.

Brain death is an irreversible loss of all brain functions, and the assessment is crucial for organ supply for transplantation. The noninvasive, sensitive, universally available and timely ancillary method to assess brain death has not been established. Here, we attempted to explore a noninvasive way in brain death assessment. Eighteen brain‐dead patients and 20 healthy subjects were measured by near‐infrared spectroscopy (NIRS), with a multiple‐phase protocol at varied fraction of inspired O2 (FIO2). We found that the concentration changes ratios of oxyhemoglobin to deoxyhemoglobin (Δ[HbO2]/Δ[Hb]) in the cerebral cortex of brain‐dead patients were significantly higher than those of healthy subjects. And, the Δ[HbO2]/Δ[Hb] in low‐to‐high FIO2 phase was most sensitive to distinguish brain‐dead patients from healthy subjects, with a recommended threshold ranged in 1.40~1.50. The innovative incorporation of NIRS and a varied FIO2 protocol was shown to be a noninvasive and reliable way in assessing brain death. This successful attempt of NIRS application is a help for fast and accurate evaluation of brain death, promptly offering quality‐assured donor organs and indicate us a protocol‐aided way to expand the use of NIRS.

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The organoselenium-catalyzed amination of alkenes is a promising way to construct functionalized amines. However, the use of chemical oxidants and the unavoidable formation of allylic amine or enamine are the two main limitations of these methodologies. Against this background, we herein report an electro-selenocatalytic regime for the hydroazolylation of alkenes with azoles under external oxidant-free conditions with low catalyst loadings. Moreover, this protocol enables the generation of amines without vinyl substituents.

Stroke is the second leading cause of death and disability worldwide. The incidence of hemorrhagic stroke increases dramatically with the increasingly aging population. Recently, technology of low-level light/laser therapy (LLLT) is emerging as a novel noninvasive therapeutic approach to treat stroke based on effective photobiomodulation. To obtain optimal therapeutic effects, several LLLT illumination parameters such as beam size and beam type need to be optimized. However, the quantitative optimization of LLLT illumination parameters for stroke therapeutics is impractical to test directly on human subjects. In this paper, we employed a precise voxelized three-dimensional Monte Carlo method (MCVM) to simulate photon propagation within Visible Chinese human (VCH) head at different level of stroke with varied parameters of beams. By evaluation with criteria of the total fluence flux in lesion region and the maximal penetration depth, we found that Gaussian beam with larger or the same size of hemorrhagic region generates the highest and relative homogeneous therapeutic outcomes, while the Top-hat beam performed better when hemorrhagic region is much bigger than beam size. These results demonstrate the great potential of using VCH and MCVM in optimizing LLLT treatment parameters for stroke and in guiding future instrumentation of LLLT on hemorrhagic stroke.

Noninvasive monitoring of cardiac hemodynamics remains challenging in cardiovascular medicine. The possibility of noninvasive optical monitoring of cardiac hemodynamics was theoretically investigated in this study. By utilizing the Monte Carlo simulation method for voxelized media (MCVM) and Visible Chinese Human dataset, we quantified and visualized the photon migration in human thoracic region. The light fluence distribution was showed to reach heart tissue (∼3 cm depth underbody surface) and 12% of the total fluence was absorbed by the myocardium. The proportion of spatial sensitivity distribution (SSD) in cardiac tissue to the total SSD reached 0.0195%. The portion of SSD increased following with cardiac diastole and diffuse reflectance deceased linearly with increasing cardiac volume. The optimal separation between the light source and detector was provided to be 3.5 to 4.0 cm for future development of noninvasive cardiac hemodynamics monitoring. A pilot experimental study was conducted to measure the diffuse reflectance light and fingertip photoplethysmography. These data suggest that the fluctuation period of near‐infrared (NIR) diffuse reflectance was consistent with the cardiac cycle, while the fluctuation features of the NIR signal was not consistent with that of photoplethysmography. All results indicate the great potential of noninvasive optical monitoring of myocardial hemodynamics.

A novel optical element, vaulted axicon, is proposed for the first time in this paper. We analyze the distribution of light field with diffraction theory, and simulate the intensity distribution behind vaulted axicon. The result shows that multi-bottle beam can be obtained after a plane wave has passed through an vaulted axicon, moreover the intensity of the bottle beam is very high in the focal region because of the energy of spherical wave is significant concentrated in this region. The simulation and comparison show that the intensity around the bottle beam generated by vaulted axicon is far higher than that generated by superposition of two Bessel beams, therefore the particle trapping efficiency can be significantly increased. By comparing the scattering forces of bottle beam generated by the two methods, we demonstrate that the bottle beam generated by vaulted axicon is superior in particle trapping.

Monte Carlo simulation is a precise method to model light propagation in bio-tissues and has been considered the golden standard to estimate the result of other computation methods. But the huge computation burden limited the application. In this paper, we propose a parallel computing model using graphic card to accelerate the Monte Carlo simulation in 3-D voxelized media with the consideration of internal refraction. Optimization of the parallel mode is made by using segmentations and offered an extra boost of simulation speed. The acceleration efficiency affecting factors are investigated and the acceleration rate of the five segmented model is 32.6 times higher than non-GPU model and 1.66 times higher than non-optimized model for a real human head 3-D structure simulation. INDEX TERMS Bio-tissue, graphic card acceleration, light propagation, Monte Carlo simulation, parallel mode.