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Micromachines May 2024The creation of multi-channel focused beams with arbitrary polarization states and their corresponding optical torques finds effective applications in the field of...
The creation of multi-channel focused beams with arbitrary polarization states and their corresponding optical torques finds effective applications in the field of optical manipulation at the micro-nanoscale. The existing metasurface-based technologies for polarization rotation have made some progress, but they have been limited to single functions and have not yet achieved the generation of full polarization. In this work, we propose a multi-channel and spatial-multiplexing interference strategy for the generation of multi-channel focusing beams with arbitrary polarization rotation based on all-dielectric birefringent metasurfaces via simultaneously regulating the propagation phase and the geometric phase and independently controlling the wavefronts at different circular polarizations. For the proof of concept, we demonstrate highly efficient multi-channel polarization rotation meta-devices. The meta-devices demonstrate ultra-high polarization extinction ratios and high focusing efficiencies at each polarization channel. Our work provides a compact and versatile wavefront-shaping methodology for full-polarization control, paving a new path for planar multifunctional meta-optical devices in optical manipulation at micro-nano dimensions.
PubMed: 38930680
DOI: 10.3390/mi15060710 -
IEEE Journal of Biomedical and Health... Jun 2024Monitoring spine kinematics is crucial for applications like disease evaluation and ergonomics analysis. However, the small scale of vertebrae and the number of degrees...
BACKGROUND
Monitoring spine kinematics is crucial for applications like disease evaluation and ergonomics analysis. However, the small scale of vertebrae and the number of degrees of freedom present significant challenges for noninvasive and convenient spine kinematics estimation.
METHODS
This study developed a dynamic optimization framework for wearable spine motion tracking at the intervertebral joint level by integrating smartphone videos and Inertia Measurement Units (IMUs) with dynamic constraints from a thoracolumbar spine model. Validation involved motion data from 10 healthy males performing static standing, dynamic upright trunk rotations, and gait. This data included rotations of ten IMUs on vertebrae and virtual landmarks from three smartphone videos preprocessed by OpenCap, an application leveraging computer vision for pose estimation. The kinematic measures derived from the optimized solution were compared against simultaneously collected infrared optical marker-based measurements and in vivo literature data. Solutions only based on IMUs or videos were also compared for accuracy evaluation.
RESULTS
The proposed optimization approach closely matched the reference data in the intervertebral or segmental rotation range, demonstrating minimal angular differences across all motions and the highest correlation in 3D rotations (maximal Pearson and intraclass correlation coefficients of 0.92 and 0.94, respectively). Time-series changes of joint angles also aligned well with the optical-marker reference.
CONCLUSION
Dynamic optimization of the spine simulation that integrates IMUs and computer vision outperforms the single-modality method.
SIGNIFICANCE
This markerless 3D spine motion capture method holds potential for spinal health assessment in large cohorts in real-world settings without dedicated laboratories.
PubMed: 38923475
DOI: 10.1109/JBHI.2024.3419591 -
Marine Drugs Jun 2024Three polysaccharides (SnNG, SnFS and SnFG) were purified from the body wall of . The physicochemical properties, including monosaccharide composition, molecular weight,...
Three polysaccharides (SnNG, SnFS and SnFG) were purified from the body wall of . The physicochemical properties, including monosaccharide composition, molecular weight, sulfate content, and optical rotation, were analyzed, confirming that SnFS and SnFG are sulfated polysaccharides commonly found in sea cucumbers. The highly regular structure {3)-L-Fuc-(α1,} of SnFS was determined via a detailed NMR analysis of its oxidative degradation product. By employing β-elimination depolymerization of SnFG, tri-, penta-, octa-, hendeca-, tetradeca-, and heptadeca-saccharides were obtained from the low-molecular-weight product. Their well-defined structures confirmed that SnFG possessed the backbone of {-GalNAc-β(1,4)--GlcA}, and each GlcA residue was branched with Fuc. SnFS and SnFG are both structurally the simplest version of natural fucan sulfate and fucosylated glycosaminoglycan, facilitating the application of low-value sea cucumbers . Bioactivity assays showed that SnFG and its derived oligosaccharides exhibited potent anticoagulation and intrinsic factor Xase (iXase) inhibition. Moreover, a comparative analysis with the series of oligosaccharides solely branched with Fuc showed that in oligosaccharides with lower degrees of polymerization, such as octasaccharides, Fuc led to a greater increase in APTT prolongation and iXase inhibition. As the degree of polymerization increases, the influence from the sulfation pattern diminishes, until it is overshadowed by the effects of molecular weight.
Topics: Animals; Anticoagulants; Polysaccharides; Oligosaccharides; Molecular Weight; Stichopus; Sea Cucumbers; Sulfates; Magnetic Resonance Spectroscopy; Blood Coagulation
PubMed: 38921576
DOI: 10.3390/md22060265 -
ACS Omega Jun 2024Five racemates () were isolated from , in which were successfully separated into four pairs of enantiomers ( and , and , and , and and ), whereas the resolution of...
Five racemates () were isolated from , in which were successfully separated into four pairs of enantiomers ( and , and , and , and and ), whereas the resolution of failed due to the hemiacetal functionality at the stereogenic center. Using electronic circular dichrosim calculation, the relationship of the molecular rotation direction and the carbon / chirality was revealed, and each pair of enantiomer was identified as (-)-()-gentianmacrol B () and (+)-()-gentianmacrol B (), (-)-()-8-methoxy-gentianol () and (+)-()-8-methoxy-gentianol (), (+)-()-8-methyl-gentianadine () and (-)-()-8-methyl-gentianadine (), and (-)-()-gentianol () and (+)-()-gentianol (). Besides, these compounds could be divided into two series, containing the benzene ring moiety and containing the pyridine ring moiety. Considering that their molecular skeleton could not be generated from the classical biosynthesis pathway in plants, the plausible biosynthesis pathways of were deduced to be transformed from secoiridoids in . Due to the significant difference in the pharmacological effect for the optical factor, our research provided new diverse molecules for further optical activity studies in drug research.
PubMed: 38911760
DOI: 10.1021/acsomega.4c02476 -
Phytochemistry Jun 2024Herein, 17 previously undescribed polyacetylenes and 9 known ones were isolated from Tridax procumbens L. Their structures were identified using spectroscopic techniques...
Herein, 17 previously undescribed polyacetylenes and 9 known ones were isolated from Tridax procumbens L. Their structures were identified using spectroscopic techniques (NMR, UV, IR, MS and optical rotation), the modified Mosher method, electronic circular dichroism (ECD) data and ECD calculation. The cytotoxicity of polyacetylenes on six human tumour cell lines (K562, K562/ADR, AGS, MGC-803, SPC-A-1 and MDA-MB-231) was evaluated. (3S,10R)-tridaxin B (2a), (3S,10S)-tridaxin B (2b) and tridaxin F (8) demonstrated substantial cytotoxic effects against the K562 cell line, with half-maximal inhibitory concentration (IC) values of 2.62, 14.43 and 17.91 μM, respectively. Cell and nucleus morphology assessments and Western blot analysis confirmed that the cytotoxicity of the three polyacetylenes on K562 cells was mediated through a dose-dependent apoptosis pathway. Furthermore, (3S,10R)-tridaxin A (1a) and tridaxin G (9) exhibited considerable inhibitory effects on lipopolysaccharide-stimulated nitric oxide production in RAW 264.7 macrophages, with IC values of 15.92 and 20.35 μM, respectively. Further investigations revealed that 9 exerted anti-inflammatory activities by impeding the nuclear translocation of NF-κB and down-regulating the expression of pro-inflammatory factors, including those of iNOS, COX-2, IL-1β and IL-6, in a concentration-dependent manner. The study provides evidence that polyacetylenes from T. procumbens may serve as a potential source of anti-tumour or anti-inflammatory agents for treating related diseases.
PubMed: 38901625
DOI: 10.1016/j.phytochem.2024.114191 -
Sensors (Basel, Switzerland) May 2024Recently, inertial measurement units have been gaining popularity as a potential alternative to optical motion capture systems in the analysis of joint kinematics. In a...
Recently, inertial measurement units have been gaining popularity as a potential alternative to optical motion capture systems in the analysis of joint kinematics. In a previous study, the accuracy of knee joint angles calculated from inertial data and an extended Kalman filter and smoother algorithm was tested using ground truth data originating from a joint simulator guided by fluoroscopy-based signals. Although high levels of accuracy were achieved, the experimental setup leveraged multiple iterations of the same movement pattern and an absence of soft tissue artefacts. Here, the algorithm is tested against an optical marker-based system in a more challenging setting, with single iterations of a loaded squat cycle simulated on seven cadaveric specimens on a force-controlled knee rig. Prior to the optimisation of local coordinate systems using the REference FRame Alignment MEthod (REFRAME) to account for the effect of differences in local reference frame orientation, root-mean-square errors between the kinematic signals of the inertial and optical systems were as high as 3.8° ± 3.5° for flexion/extension, 20.4° ± 10.0° for abduction/adduction and 8.6° ± 5.7° for external/internal rotation. After REFRAME implementation, however, average root-mean-square errors decreased to 0.9° ± 0.4° and to 1.5° ± 0.7° for abduction/adduction and for external/internal rotation, respectively, with a slight increase to 4.2° ± 3.6° for flexion/extension. While these results demonstrate promising potential in the approach's ability to estimate knee joint angles during a single loaded squat cycle, they highlight the limiting effects that a reduced number of iterations and the lack of a reliable consistent reference pose inflicts on the sensor fusion algorithm's performance. They similarly stress the importance of adapting underlying assumptions and correctly tuning filter parameters to ensure satisfactory performance. More importantly, our findings emphasise the notable impact that properly aligning reference-frame orientations before comparing joint kinematics can have on results and the conclusions derived from them.
Topics: Humans; Biomechanical Phenomena; Knee Joint; Algorithms; Range of Motion, Articular; Cadaver; Movement; Male; Knee
PubMed: 38894115
DOI: 10.3390/s24113324 -
Journal of the American Chemical Society Jun 2024Complex micro/nanorobots may be constructed by integrating several independent, controlled nanomotors for high degrees of freedom of maneuvering and manipulation....
Complex micro/nanorobots may be constructed by integrating several independent, controlled nanomotors for high degrees of freedom of maneuvering and manipulation. However, designing nanomotors with distinctive responses to the same global stimuli is challenging due to the nanomotors' simple structure and limited material composition. In this work, we demonstrate that a nanomotor can be designed with the same principles of electronic circuits, where the motion of semiconductor particles can be controlled with synchronized electric and optical signals. This technique relies on transient bipolar photoelectrochemistry in semiconductor microparticles, where the reaction site selectivity is realized by modulating the light pulse in the time domain. Due to the microparticles' intrinsic resistance and surface capacitance, the nanomotors can be designed as an electronic circuit, enabling distinctive responses to the global electric/optical field and achieving the desired movement or deflection/rotation. This work gives new insight into the manipulation technique for independent and untethered nanomotor control. Ultimately, it exploits the potential for particle sorting based on geometry in time and frequency domain modulation.
PubMed: 38877992
DOI: 10.1021/jacs.4c03810 -
Optics Letters Jun 2024Enhancing and flexibly controlling the Goos-Hänchen (GH) shift directly is a significant challenge. Here, we report a tunable giant GH shift in a Au-ReS-graphene...
Enhancing and flexibly controlling the Goos-Hänchen (GH) shift directly is a significant challenge. Here, we report a tunable giant GH shift in a Au-ReS-graphene heterostructure. The GH shift of this heterostructure demonstrates strong anisotropy and a unique "sign inversion" feature as the graphene reaches a specific thickness. Flexible control and enhancement of the GH shift to the centimeter scale can be achieved by simply rotating the crystallization direction of the heterostructure. Utilizing this feature, we designed an anisotropic refractive index sensor with a high sensitivity of 1.31 × 10µm/RIU. This marks an order of magnitude improvement over previous research and introduces a rotation-dependent sensitivity adjustment feature. The tunable giant GH shift provides a promising approach for future designs of optical sensing and modulation devices.
PubMed: 38875651
DOI: 10.1364/OL.528817 -
Optics Letters Jun 2024High-performance atomic magnetometers (AMs) rely on the measurement of optical rotation, which requires a set of bulky polarization optics that limit their applications...
High-performance atomic magnetometers (AMs) rely on the measurement of optical rotation, which requires a set of bulky polarization optics that limit their applications in scenarios where portability and compactness are necessary. In this study, a miniaturized AM is constructed based on a cubic Rb vapor cell and monolithic metalens, which provides an integrated scheme to achieve optical rotation detection induced by the circular birefringence of polarized atoms. The designed metalens achieves polarization splitting with deflection angles of ±10 and focusing with efficiencies of approximately 30% for orthogonal linear polarizations. The sensitivity of our compact device is ∼30 fT/Hz with a dynamic range of around ±1.45 nT. We envision that the presented approach paves the way for the chip integration of emerging atomic devices, which are in demand for applications such as biomagnetic imaging and portable atomic gyroscopes.
PubMed: 38875621
DOI: 10.1364/OL.527932 -
Science Advances Jun 2024Precision interferometry with quantum states has emerged as an essential tool for experimentally answering fundamental questions in physics. Optical quantum...
Precision interferometry with quantum states has emerged as an essential tool for experimentally answering fundamental questions in physics. Optical quantum interferometers are of particular interest because of mature methods for generating and manipulating quantum states of light. Their increased sensitivity promises to enable tests of quantum phenomena, such as entanglement, in regimes where tiny gravitational effects come into play. However, this requires long and decoherence-free processing of quantum entanglement, which, for large interferometric areas, remains unexplored territory. Here, we present a table-top experiment using maximally path-entangled quantum states of light in a large-scale interferometer sensitive enough to measure the rotation rate of Earth. The achieved sensitivity of 5 μrad s constitutes the highest rotation resolution ever reached with optical quantum interferometers. Further improvements to our methodology will enable measurements of general-relativistic effects on entangled photons, allowing the exploration of the interplay between quantum mechanics and general relativity, along with tests for fundamental physics.
PubMed: 38875336
DOI: 10.1126/sciadv.ado0215