Application of functional near-infrared spectroscopy in the healthcare industry:A review

Functional near-infrared spectrosoopy(NIRS),a growing neuroimaging modality,has been utilized over the past few decades to understand the neuronal behavior in the brain.The technique has been used to assess the brain hemodynamics of impaired cohorts as well as able-bodied.Neuroimaging is a critical technique for patients with inpaired cognitive or motor behaviors.The portable nature of the fNIRS system is suitable for frequent monitoring of the patients who exhibit impaired brain activity.This study comprehensively reviews brain impaired patients:The studies involving patient populations and the diseases discussed in more than 10 works are included.Eleven diseases examined in this paper include autism spectrum disorder,attentiondeficit hyperactivity disorder,epilepsy,depressive disorders,anxiety and panic disorder,schizophrenia,mild cognitive impairment,Alzheimer's disease,Parkinson's disease,stroke,and traumatic brain injury.For each disease,the tasks used for exarmination,NIRS variables,and significant findings on the impairment are discussed.The channel configurations and the regions of interest are also outlined.Detecting the occurrence of symptoms at an earlier stage is vital for better rehabilitation and faster recovery.This paper ilustrates the usability of fNIRS for early detection of inpairment and the usefulness in monitoring the rehabilitation process.Finally,the limitations of the current fNIRS systems(ie,nonexistence of a standard method and the lack of well-established features for classification)and future research directions are discussed.The authors hope that the findings in this paper would lead to advanced breakthrough discoveries in the fNIRS field in the future.

RGD peptide and graphene oxide co-functionalized PLGA nanofiber scaffolds for vascular tissue engineering

In recent years,much research has been suggested and examined for the development of tissue engineering scaffolds to promote cellular behaviors.In our study,RGD peptide and graphene oxide(GO)co-functionalized poly(lactide-co-glycolide,PLGA)(RGD-GO-PLGA)nanofiber mats were fabricated via electrospinning,and their physicochemical and thermal properties were characterized to explore their potential as biofunctional scaffolds for vascular tissue engineering.Scanning electron microscopy images revealed that the RGD-GO-PLGA nanofiber mats were readily fabricated and composed of randomoriented electrospun nanofibers with average diameter of 558nm.The successful co-functionalization of RGD peptide and GO into the PLGA nanofibers was confirmed by Fourier-transform infrared spectroscopic analysis.Moreover,the surface hydrophilicity of the nanofiber mats was markedly increased by co-functionalizing with RGD peptide and GO.It was found that the mats were thermally stable under the cell culture condition.Furthermore,the initial attachment and proliferation of primarily cultured vascular smoothmuscle cells(VSMCs)on the RGD-GO-PLGA nanofibermats were evaluated.It was revealed that the RGD-GO-PLGA nanofibermats can effectively promote the growth of VSMCs.In conclusion,our findings suggest that the RGD-GO-PLGA nanofiber mats can be promising candidates for tissue engineering scaffolds effective for the regeneration of vascular smooth muscle.

Detection of primary RGB colors projected on a screen using fNIRS

In this study,functional near-infrared spectroscopy(fNIRS)is utilized to measure the hemodynamic responses(HRs)in the visual cortex of 14 subjects(aged 22–34 years)viewing the primary red,green,and blue(RGB)colors displayed on a white screen by a beam projector.The spatiotemporal characteristics of their oxygenated and deoxygenated hemoglobins(HbO and HbR)in the visual cortex are measured using a 15-source and 15-detector optode con¯guration.To see whether the activation maps upon RGB-color stimuli can be distinguished or not,the t-values of individual channels are averaged over 14 subjects.To¯nd the best combination of two features for classi¯cation,the HRs of activated channels are averaged over nine trials.The HbO mean,peak,slope,skewness and kurtosis values during 2–7 s window for a given 10 s stimulation period are analyzed.Finally,the linear discriminant analysis(LDA)for classifying three classes is applied.Individually,the best classi¯cation accuracy obtained with slope-skewness features was 74.07%(Subject 1),whereas the best overall over 14 subjects was 55.29%with peak-skewness combination.Noting that the chance level of 3-class classi¯cation is 33.33%,it can be said that RGB colors can be distinguished.The overall results reveal that fNIRS can be used for monitoring purposes of the HR patterns in the human visual cortex.

Static and adaptive feedback control for synchronization of different chaotic oscillators with mutually Lipschitz nonlinearities

This paper addresses the control law design for synchronization of two different chaotic oscillators with mutually Lipschitz nonlinearities. For analysis of the properties of two different nonlinearities, an advanced mutually Lipschitz condition is proposed. This mutually Lipschitz condition is more general than the traditional Lipschitz condition. Unlike the latter, it can be used for the design of a feedback controller for synchronization of chaotic oscillators of different dynamics. It is shown that any two different Lipschitz nonlinearities always satisfy the mutually Lipschitz condition. Applying the mutually Lipschitz condition, a quadratic Lyapunov function and uniformly ultimately bounded stability, easily designable and implementable robust control strategies utilizing algebraic Riccati equation and linear matrix inequalities, are derived for synchronization of two distinct chaotic oscillators. Furthermore, a novel adaptive control scheme for mutually Lipschitz chaotic systems is established by addressing the issue of adaptive cancellation of unknown mismatch between the dynamics of different chaotic systems. The proposed control technique is numerically tested for synchronization of two different chaotic Chua＇s circuits and for obtaining identical behavior between the modified Chua＇s circuit and the R6ssler system.

Optical Vernier sampling using a dual-comb-swept laser to solve distance aliasing

Optical interferometry using comb-swept lasers has the advantage of efficiently reducing the acquisition bandwidth for high-speed and long-range detection. However, in general, the use of a comb-swept laser involves a critical limitation in that the absolute distance cannot be measured, and, thus, multiple layers cannot be distinguished when measuring each position. This is because of the distance ambiguity induced by optical aliasing, in which there is periodic repetition of the frequency of an interferometric signal owing to discrete spectral sweeping, which does not occur in conventional optical interferometry that uses a continuous swept laser. In this paper, we introduce an optical Vernier sampling method using a dual-comb-swept laser to measure the absolute distances in a multi-layer target. For this, we designed a new type of dual-comb-swept laser to include two different free spectral ranges(FSRs) in separated wavelength bands to provide a stable lasing condition. Using a principle similar to that of a Vernier caliper for length measurement, the two different FSRs can be used to recover a higher frequency of an optical interferometric signal to measure longer distances from different layers in a target.Using the dual-comb-swept laser in optical interferometry, we solved the optical aliasing issue and measured the absolute distances of three layers separated over 83 mm using a point-scanning imaging setup and the simultaneous absolute distance of the top surfaces separated over 45 mm using a full-field imaging setup at14 and 8 times lower acquisition bandwidth than a conventional continuous swept laser that is based on optical interferometry.

Semi-crystalline photovoltaic polymers with siloxane-terminated hybrid side-chains

Three types of semi-cry stalline photovoltaic polymers were synthesized by incorporating a siloxane-terminated organic/inorganic hybrid side-chain and changing the number of fluorine substituents.A branch point away from a polymer main backbone in the siloxane-containing side-chains and the intra-and/or interchain noncovalent coulombic interactions enhance a chain planarity and facile interchain organization.The resulting polymers formed strongly agglomerated films with high roughness,suggesting strong intermolecular interactions.The optical band gap of ca.1.7 eV was measured for all polymers with a pronounced shoulder peak due to tight π-π stacking.With increasing the fluorine substituents,the frontier energy levels decreased and preferential face-on orientation was observed.The siloxane-terminated side-chains and fluorine substitution promoted the intermolecular packing,showing well resolved lamellar scatterings up to(300) for this series of polymers in the grazing incidence wide angle X-ray scattering measurements.The PPsiDTBT,PPsiDTFBT and PPsiDT2 FBT devices showed a power conversion efficiency of 3.16%,4.40%and 5.65%,respectively,by blending with PC_(71)BM.Langevin-type bimolecular charge recombination was similar for three polymeric solar cells.The main loss in the photocurrent generation for PPsiDTBT:PC_(71)BM was interpreted to originate from the trap assisted charge recombination by measuring light-intensity dependent short-circuit current density(J_(SC)) and open-circuit voltage(V_(Oc)).Our results provide a new insight into the rational selection of solubilizing substituents for optimizing crystalline interchain packing with appropriate miscibility with PC71 BM for further optimizing polymer solar cells.

Fabrication of carbon coated gadolinia particles for dual-mode magnetic resonance and fluorescence imaging

In the present study,we report a fabrication of dual-mode carbon coated gadolinia C@Gd_(2)O_(3)particles by a facile hydrothermal synthesis method without using any organic solvents.The prepared C@Gd_(2)O_(3)particles have a core-shell structure and a narrow size distribution in the range of 261±27 nm.The fluorescent properties of the prepared C@Gd_(2)O_(3)particles were accessed by a room-temperature photoluminescence study,while the longitudinal relaxivity(r1)was examined by using a clinical 1.5 T MRI scanner.A murine fibroblast L-929 cell line was used to examine the cytotoxicity and capability of the prepared C@Gd_(2)O_(3)particles for the fluorescent labeling.The obtained results show that the prepared C@Gd_(2)O_(3)particles could be used as a dual-mode contrast agent for magnetic resonance and fluorescence imaging.

Strain-tunable optical microlens arrays with deformable wrinkles for spatially coordinated image projection on a security substrate

As a new concept in materials design,a variety of strategies have been developed to fabricate optical microlens arrays(MLAs)that enable the miniaturization of optical systems on the micro/nanoscale to improve their characteristic performance with unique optical functionality.In this paper,we introduce a cost-effective and facile fabrication process on a large scale up to~15 inches via sequential lithographic methods to produce thin and deformable hexagonally arranged MLAs consisting of polydimethylsiloxane(PDMS).Simple employment of oxygen plasma treatment on the prestrained MLAs effectively harnessed the spontaneous formation of highly uniform nanowrinkled structures all over the surface of the elastomeric microlenses.With strain-controlled tunability,unexpected optical diffraction patterns were characterized by the interference combination effect of the microlens and deformable nanowrinkles.Consequently,the hierarchically structured MLAs presented here have the potential to produce desirable spatial arrangements,which may provide easily accessible opportunities to realize microlens-based technology by tunable focal lengths for more advanced micro-optical devices and imaging projection elements on unconventional security substrates.