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Nanomaterials (Basel, Switzerland) Jun 2024Single-walled carbon nanotube (SWCNT) thin films were synthesized by using a floating catalyst chemical vapor deposition (FCCVD) method with a low flow rate (200 sccm)...
Single-walled carbon nanotube (SWCNT) thin films were synthesized by using a floating catalyst chemical vapor deposition (FCCVD) method with a low flow rate (200 sccm) of mixed gases (Ar and H). SWCNT thin films with different thicknesses can be prepared by controlling the collection time of the SWCNTs on membrane filters. Transmission electron microscopy (TEM) showed that the SWCNTs formed bundles and that they had an average diameter of 1.46 nm. The Raman spectra of the SWCNT films suggested that the synthesized SWCNTs were very well crystallized. Although the electrical properties of SWCNTs have been widely studied so far, the Hall effect of SWCNTs has not been fully studied to explore the electrical characteristics of SWCNT thin films. In this research, Hall effect measurements have been performed to investigate the important electrical characteristics of SWCNTs, such as their carrier mobility, carrier density, Hall coefficient, conductivity, and sheet resistance. The samples with transmittance between 95 and 43% showed a high carrier density of 10-10 cm. The SWCNTs were also treated using Brønsted acids (HCl, HNO, HSO) to enhance their electrical properties. After the acid treatments, the samples maintained their p-type nature. The carrier mobility and conductivity increased, and the sheet resistance decreased for all treated samples. The highest mobility of 1.5 cm/Vs was obtained with the sulfuric acid treatment at 80 °C, while the highest conductivity (30,720 S/m) and lowest sheet resistance (43 ohm/square) were achieved with the nitric acid treatment at room temperature. Different functional groups were identified in our synthesized SWCNTs before and after the acid treatments using Fourier-Transform Infrared Spectroscopy (FTIR).
PubMed: 38869591
DOI: 10.3390/nano14110965 -
Journal of Science and Medicine in Sport May 2024Birthweight (BW) indicates newborn health and is a risk factor for development of chronic diseases later in life. The aim was to investigate whether or not prenatal...
OBJECTIVES
Birthweight (BW) indicates newborn health and is a risk factor for development of chronic diseases later in life. The aim was to investigate whether or not prenatal physical activity (PA) influences BW extremes and how PA influences BW extremes in those diagnosed with pregnancy-related diseases.
DESIGN
We performed a scoping review.
METHODS
Searches were completed on five databases and studies identified were uploaded to Covidence.
RESULTS
Across the five databases 3114 studies were identified and after screening, 69 of these studies were used for the final review. Of the 61 studies that considered low BW (LBW)/small for gestational age (SGA) infants, the majority of results (69 %) indicated that PA during pregnancy had no significant impact on LBW or SGA infants. In addition, 11 % of studies reported a significant decrease in the prevalence of LBW infants, however two studies (3 %) reported a significant increase in LBW or SGA infants, likely relating to individuals with high body mass index and poor adherence to PA. Of the 41 studies that did report LGA/macrosomia, 34 % reported that PA significantly reduced the prevalence of higher BW infants. One study reported the association between meeting exercise recommendations and reducing the odds of LGA infants in those with pregnancy-related diseases.
CONCLUSIONS
We provide evidence on the association of prenatal PA with BW extremes. It is suggested that prenatal PA does not increase the risk of delivering LBW/SGA infants and may reduce the prevalence of large BW infants. Further research is needed to confirm these relationships and explain their underlying mechanisms.
PubMed: 38866653
DOI: 10.1016/j.jsams.2024.05.016 -
Optics Express Jun 2024Cascaded Raman Fiber Lasers (CRFLs) are wavelength versatile sources that can provide power at any wavelength in the Near-Infrared (NIR) region. Conventional CRFLs with...
Cascaded Raman Fiber Lasers (CRFLs) are wavelength versatile sources that can provide power at any wavelength in the Near-Infrared (NIR) region. Conventional CRFLs with broadband feedback are widely wavelength tunable but have broad line widths. A feedback mechanism must be used to reduce the broadening of the linewidth without compromising the wavelength tunability. Here, we propose to use a dual feedback mechanism that combines broadband feedback at all wavelengths, using a flat cleave, with filtered feedback at a desired wavelength due to a grating filter. This allows substantial linewidth reduction of CRFLs up to the 6 Raman shifts, from 1100 nm to 1500 nm, and can be extended further. Significantly reduced linewidth with multi-watt in-band output power is achieved with fine wavelength tuning within each Raman Stokes band using a fixed wavelength pump. As an application of linewidth narrowed output, we performed frequency doubling of CRFL output to generate over 100 mW of wavelength tunable yellow-green and yellow output with enhanced efficiency.
PubMed: 38859440
DOI: 10.1364/OE.524166 -
Optics Express Apr 2024High power 509 nm continuous-wave (CW) lasers have important applications in science and communication. Here we demonstrate a robust high-power single-frequency 509 nm...
High power 509 nm continuous-wave (CW) lasers have important applications in science and communication. Here we demonstrate a robust high-power single-frequency 509 nm laser system based on nonlinear phase demodulation technique and single-pass second harmonic generation (SHG) configuration. In experiments, the single-frequency fundamental wave at 1018 nm was linewidth-broadened by an electro-optical modulator and then amplified to 207 W in a ytterbium-doped fiber amplifier. In subsequent single-pass SHG stage, over 20 W CW single-frequency 509 nm laser was generated in a LiBO crystal with a SHG efficiency of 9.7%. To the best of our knowledge, this is the highest reported power for CW single-frequency 509 nm laser, which could be used for advanced underwater optical communication and preparation of cesium Rydberg state.
PubMed: 38859408
DOI: 10.1364/OE.521926 -
Optics Express Apr 2024We report a 4.3 µm mid-infrared (mid-IR) high-power amplified spontaneous emission (ASE) fiber source based on CO-filled nested hollow-core anti-resonant fiber...
We report a 4.3 µm mid-infrared (mid-IR) high-power amplified spontaneous emission (ASE) fiber source based on CO-filled nested hollow-core anti-resonant fiber (Nested HC-ARF). The pump source is a homemade hundred-watt-level wavelength-tunable 2 µm single-frequency fiber laser. A 5.7 m long 8-tube Nested HC-ARF is used as the gas cell, with a core diameter of 110 µm and cladding diameter of 400 µm, which exhibits transmission loss of 0.1 dB/m at 2 µm and 0.24 dB/m at 4.3 µm respectively. To improve the coupling efficiency of the high-power pump laser and reduce the influence of the thermal effect at the input end of the hollow-core fiber, the fiber is designed for multimode transmission at the pump wavelength. A continuous wave output power of 6.6 W at 4.3 µm is achieved, and the slope efficiency is 17.05%. To the best of our knowledge, it is the highest output power for such gas-filled HC-ARF ASE sources in 4∼5 µm. This work demonstrates the great potential of gas-filled HC-ARF generating high-power mid-IR emission.
PubMed: 38859395
DOI: 10.1364/OE.517713 -
Optics Express Apr 2024In this paper, a hundred-watt-level near-diffraction-limited step-index Yb-doped fiber (YDF) laser near 980 nm is demonstrated firstly, to the best of our knowledge. By...
In this paper, a hundred-watt-level near-diffraction-limited step-index Yb-doped fiber (YDF) laser near 980 nm is demonstrated firstly, to the best of our knowledge. By using the 11.7-W 979-nm single-mode seed light, the in-band amplified spontaneous emission (ASE) is well suppressed and the maximum output power of 101.5 W with the beam quality (M factor) of 1.285 was obtained. This work does not only propose an effective method for the suppression of in-band ASE, but also provides a cost-effective solution of hundred-Watt-level near-diffraction-limited fiber lasers near 980 nm.
PubMed: 38859289
DOI: 10.1364/OE.517764 -
Optics Express May 2024We report on the Czochralski crystal growth, polarized optical spectroscopy, and the first continuous-wave laser operation of 1.5 at.% Tm:LuVO crystal on the H → H...
We report on the Czochralski crystal growth, polarized optical spectroscopy, and the first continuous-wave laser operation of 1.5 at.% Tm:LuVO crystal on the H → H transition. The polarized absorption and stimulated-emission properties of Tm ions in LuVO were revised and the crystal-field splitting of the Tm multiplets was determined by low-temperature (12 K) spectroscopy. The maximum stimulated-emission cross-section for the H → H transition is 2.48 × 10 cm at 2363 nm for π-polarization corresponding to an emission bandwidth of 28 nm. Evidence of phonon-assisted emissions of Tm ions above 2 µm is presented. The broadband emission properties of the Tm:LuVO crystal make it promising for ultrashort pulse generation. Additionally, pumped by a 796 nm fiber-coupled laser diode, the Tm:LuVO laser generated a Watt-level output power at 2279-2295 nm with a slope efficiency of 9.2% and linearly polarized emission (π-polarization).
PubMed: 38859092
DOI: 10.1364/OE.517124 -
Scientific Reports Jun 2024Data-driven approaches are often utilized to model and generate vibrotactile feedback and sounds for rigid stylus-based interaction. Nevertheless, in prior research,...
Data-driven approaches are often utilized to model and generate vibrotactile feedback and sounds for rigid stylus-based interaction. Nevertheless, in prior research, these two modalities were typically addressed separately due to challenges related to synchronization and design complexity. To this end, we introduce a novel multimodal multitask deep learning framework. In this paper, we developed a comprehensive end-to-end data-driven system that encompasses the capture of contact acceleration signals and sound data from various texture surfaces. This framework introduces novel encoder-decoder networks for modeling and rendering vibrotactile feedback through an actuator while routing sound to headphones. The proposed encoder-decoder networks incorporate stacked transformers with convolutional layers to capture both local variability and overall trends within the data. To the best of our knowledge, this is the first attempt to apply transformer-based data-driven approach for modeling and rendering of vibrotactile signals as well as sounds during tool-surface interactions. In numerical evaluations, the proposed framework demonstrates a lower RMS error compared to state-of-the-art models for both vibrotactile signals and sound data. Additionally, subjective similarity evaluation also confirm the superiority of proposed method over state-of-the-art.
PubMed: 38858511
DOI: 10.1038/s41598-024-64376-y -
Scientific Reports Jun 2024In this work we demonstrate a miniaturised imaging system based around a time-gated SPAD array operating in a "chip-on-tip" manner. Two versions of the system are...
In this work we demonstrate a miniaturised imaging system based around a time-gated SPAD array operating in a "chip-on-tip" manner. Two versions of the system are demonstrated, each measuring 23 mm × 23 mm × 28 mm with differing fields of view and working distances. Initial tests demonstrate contrast between materials in widefield fluorescence imaging (WFLIm) mode, with frame rates of > 2 Hz achievable. Following this, WFLIm images of autofluorescence in ovine lung tissue are obtained at frame rates of ~ 1 Hz. Finally, the ability of the second system to perform simultaneous WFLIm and time of flight (aka Flourescence Lifetime Imaging Distance and Ranging, FLImDAR) is also tested. This shows that the system is capable of 4 mm resolution of object separation when tested on 3D printed samples. It is further demonstrated as being able to perform scene reconstruction on autofluorescent lung tissue. This system is, to date, the smallest chip on tip WFLIm system published, and is the first demonstration of the FLImDAR technique in a compact, portable system.
PubMed: 38858419
DOI: 10.1038/s41598-024-63409-w -
Exploration of Medicine 2024Endothelial dysfunction has been associated with both cerebrovascular pathology and Alzheimer's disease (AD). However, the connection between circulating endothelial...
AIM
Endothelial dysfunction has been associated with both cerebrovascular pathology and Alzheimer's disease (AD). However, the connection between circulating endothelial cells and the risk of AD remains uncertain. The objective was to leverage data from the Framingham Heart Study to investigate various circulating endothelial subtypes and their potential correlations with the risk of AD.
METHODS
The study conducted data analyses using Cox proportional hazard regression and linear regression methods. Additionally, genome-wide association study (GWAS) was carried out to further explore the data.
RESULTS
Among the eleven distinct circulating endothelial subtypes, only circulating endothelial progenitor cells (EPCs) expressing CD34+CD133+ were found to be negatively and dose-dependently associated with reduced AD risk. This association persisted even after adjusting for age, sex, years of education, apolipoprotein E () ε4 status, and various vascular diseases. Particularly noteworthy was the significant association observed in individuals with hypertension and cerebral microbleeds. Consistently, positive associations were identified between CD34+CD133+ EPCs and specific brain regions, such as higher proportions of circulating CD34+CD133+ cells correlating with increased volumes of white matter and the hippocampus. Additionally, a GWAS study unveiled that CD34+CD133+ cells influenced AD risk specifically in individuals with homozygous genotypes for variants in two stem cell-related genes: kirre like nephrin family adhesion molecule 3 (, rs580382 CC and rs4144611 TT) and exocyst complex component 6B (, rs61619102 CC).
CONCLUSIONS
The findings suggest that circulating CD34+CD133+ EPCs possess a protective effect and may offer a new therapeutic avenue for AD, especially in individuals with vascular pathology and those carrying specific genotypes of and genes.
PubMed: 38854406
DOI: 10.37349/emed.2024.00216