Search Results (20)

Photobiomodulation (PBM) has shown promising potential to enhance bone regeneration; however, its optimal delivery parameters and interactions with osteoconductive scaffolds remain insufficiently defined. This preclinical study is the first to incorporate a pilot dosimetry evaluation to standardize 980-nm PBM delivery and ensure that effective irradiance reached the target surface of critical-size calvarial defects in mice. The primary aim was to evaluate the effectiveness of this novel 980-nm PBM protocol delivered using either flat-top (FT) or standard Gaussian (ST) handpieces in enhancing bone regeneration in critical-size defects (CSDs), both with and without Bio-Oss^® grafting. A total of 120 adult mice were allocated into twelve experimental groups (n = 10 per group): untreated (control), Bio-Oss^® alone, PBM alone, and PBM combined with Bio-Oss^®, using either FT or ST handpieces, and evaluated at 30 and 60 days. Animals received 980 nm irradiation at 0.6 W (nominal power output–set on laser interface) in continuous-wave mode for 60 s, three times per week, for two consecutive weeks. Pilot dosimetry included power meter measurements to determine the therapeutic power reaching the defect surface area and temperature monitoring to ensure safe energy delivery. The dosimetry study demonstrated that, after accounting for the optical properties of mouse shaved skin and the Bio-Oss^® graft covered with Bio-Gide^® membrane, the effective irradiance reaching the base of the defect surface area was 1.131 W/cm² for the FT handpiece and 0.413 W/cm² for the ST handpiece. This dose was sufficient to induce significant regenerative effects. Histological, Masson’s trichrome, and immunohistochemical analyses for Runx2, OCN, GLI1, CD34, and CTSK were performed to characterize early and late osteogenic events. The combination of PBM and Bio-Oss^® significantly accelerated bone regeneration compared with PBM alone, with the FT handpiece producing the most uniform and advanced osteogenesis. PBM enhanced progenitor activation, osteoblast differentiation, angiogenesis, matrix deposition, and late-stage remodeling, demonstrating a synergistic effect with the scaffold, whereas Bio-Oss^® alone or defect alone showed limited early regenerative potential. These findings highlight the effectiveness of this novel standardized PBM dosimetry and uniform beam profile (FT), supporting their use as a foundation for future randomized controlled trials in craniofacial bone repair. Full article

Reliable positioning performance is crucial in precision industrial automation, especially under dynamic conditions. This research focuses on examining the accuracy of a toothed belt driven linear servo motor positioning system, with the aim of identifying the main factors influencing position deviation. The system was built on a Power Belt ITO 060M shaft, controlled by an Rtelligent RS200-G servo controller and an Omron CP1L-E PLC. Position measurement was performed by a laser distance meter and a Cognex IS2000C-130-40-SR8 industrial camera, both calibrated with certified gauge blocks. The linear unit was moved to predefined points at different speeds, accelerations, and decelerations profiles and the resulting position deviation was recorded for each case. Several analytical methods were used to evaluate the collected measurement data to determine which factors have the greatest impact on positioning error. The result showed that speed significantly affected the accuracy of the system, while the effects of deceleration and acceleration were less pronounced. The study contributes to the fine-tuning of linear motion system and the targeted improvement of their performance. Full article

This paper presents issues related to the assessment of the texture of aggregate concrete (EAC) surfaces using various methods for its verification. Microtexture was assessed using the British Pendulum Tester (BPT) and Dynamic Friction Tester (DFT). Two laser profilometers were used to assess macrotexture, circular texture meter (CTM) and stationary laser profilograph (SPL), as well as the commonly known volumetric method. Measurements were carried out on left and right tracks and in between them on five test sections of expressways. Based on the analyses performed, it was found that the results obtained by the DFT were less sensitive to changes in microtexture between individual tracks compared to the results obtained by the BPT. The BPN values in the left track were lower than those in the right track. However, the difference between the DFT20 results in these spots was insignificant. Both MPD and MTD values did not show significant differences between the right and left tracks. However, some differences were observed between the MPD parameters obtained using the CTM and SPL. This resulted from the different frequency and length of the scanned surface profile. However, the differences were at an acceptable level. A very high linear correlation was obtained in the case of BPN and DFT20 values (r − 0.719), and in the case of MPD and MTD values, the correlation was almost certain (r above 0.900). Based on a comparative analysis of the models estimating mean texture depth (MTD/ETD), a significant difference was observed between models based on EAC pavement results and those based on asphalt surfaces. Full article

A novel approach to the development of Distributed Temperature-Sensing (DTS) systems based on Raman Scattering in Multimode optical fibers operating at around 800 nm is presented, focusing on applications requiring temperature profile measurement in the range of a few hundreds of meters. In contrast to the standard Raman DTS systems, which aim to shorten the pulse space width as much as possible to improve the precision of measurement, the novel approach studied in this work is based on the use of pulses with a space width that is approximately equal to the distance covered by the fiber under test. The proposed technique relies on numerical post-processing to obtain the temperature profile measurement with a precision of about $\pm 3°\mathrm{C}$ and a spatial resolution of 8 m, due to the transaction phases of the optical pulses. This solution simplifies the electronic circuit development, also minimizing the required laser peak power needed compared to the typical narrow pulse techniques. Full article

With the development of infrastructure construction in mountainous areas, the number of new extra-long tunnels is increasing. However, these tunnels often face the challenge of complex and variable surrounding rock grades, resulting in a large number of overbreak and underbreak due to the untimely adjustment of smooth blasting parameters. This study focuses on the optimization of the peripheral hole charging structure and blasting parameters for extra-long hard rock tunnels, aiming to improve the effectiveness of smooth blasting technology. The results of this study demonstrate a significant improvement in the effect of smooth blasting after implementing bidirectional polymerization blasting in the tunnel. A comparison between the bidirectional shaped charge and spaced decoupled charge blasting reveals that the former yields better results. To obtain accurate data on the tunnel section profile during excavation, a laser cross-section meter is used for measurement. Furthermore, this study quantitatively compares the optimization effect of smooth blasting parameters. The multifractal characteristics of the tunnel profile overbreak point sequences are analyzed under different smooth blasting schemes using the multifractal detrended fluctuation analysis (MF-DFA) method. It is found that both the spaced decoupled charge and the bidirectional shaped charge blasting exhibit multifractal features in the overbreak measurement point sequences. The calculation results of the multifractal features of the tunnel profile under different smooth blasting plans are in line with the actual situation. Full article

This work presents the first instance of a silica few-mode microstructured optical fiber (MOF) being successfully fabricated with a hollow GeO₂-doped ring core and by strongly inducing twisting up to 790 revolutions per meter. Some technological issues that occurred during the manufacturing of the GeO₂-doped supporting elements for the large hollow cores are also described, which complicated the spinning of the MOFs discussed above. We also provide the results of the tests performed for the pilot samples—designed and manufactured using the untwisted and twisted MOFs described above—which were characterized by an outer diameter of 65 µm, a hollow ring core with an inner diameter of 30.5 µm, under a wall thickness of 1.7 µm, and a refractive index difference of Δn = 0.030. Moreover, their geometrical parameters, basic transmission characteristics, and the measurements of the far-field laser beam profile patterns are also provided. Full article

This work presents a fabricated silica few-mode microstructured optical fiber (MOF) with a special six GeO₂-doped core geometry, an outer diameter of 125 µm (that corresponds to conventional commercially available telecommunication optical fibers), and improved induced twisting up to 500 revolutions per 1 m (under a rotation speed of 1000 revolutions per meter with a drawing speed of ~2 m per minute). The article discusses some technological aspects and issues of manufacturing the above-described twisted MOFs with complicated structures and geometry as GeO₂-doped silica supporting elements for them. We present results of some measurements performed for fabricated samples of chiral silica six-GeO₂-doped-core few-mode MOFs with various orders of twisting and both step and graded refractive indexes of “cores”. These tests contain research on MOF geometrical parameters, attenuation, and measurements of the far-field laser beam profile. Full article

This study aimed to compare the effectiveness of a novel professional tooth-strengthening system and a conventional caries-prevention method that involved the use of high fluoride concentrations, to determine whether the system has a whitening effect. Bovine tooth-enamel samples were treated with fluoride gel (conventional APF method) or a mixture of citric acid gel, calcium phosphate (α-TCP), and fluoride gel, referred to as the CAP system; these treatments were performed to generate an acid-resistant layer on the enamel surface. For the evaluation of the acid resistance, a cyclic experiment, involving a 1-h remineralization and a 24-h acid treatment, was conducted thrice after the treatments. The height profiles were observed using a 3D-measuring laser microscope and the hardness was evaluated by Vickers hardness test. The morphological changes in the surface and cross-section of the enamel were observed by scanning electron microscopy. To evaluate the whitening effect, the enamel was ground until the color of the underlying dentin was recognizable; the CAP system was applied once, and the color change was measured using a color difference meter. As a result, it was confirmed that an acid-resistant layer was formed on the tooth surfaces treated with the CAP system, and a whitening effect was obtained. Full article

The Mars Orbiter Laser Altimeter (MOLA) Precision Experiment Data Records (PEDR) serve as the geodetic reference of Mars. However, these MOLA footprints were geolocated using outdated auxiliary information that dates back to 2003. In this study, we recompute the MOLA PEDR footprint locations and investigate the impact of the updated spacecraft orbit model and Mars rotational model on MOLA’s geolocation. We observe quasi-exponential increases near the poles of up to 30 m in the recomputation residuals for the nadir profiles. Meanwhile, we demonstrate that limitations exist in the stored MOLA PEDR attitude records, which can shift the footprint up to hundreds of meters laterally and several meters radially. The usage of the Navigation and Ancillary Information Facility (NAIF)-archived attitude information instead can circumvent this issue and avoid the approximation errors due to discrete samplings of the attitude information used in geolocation by the PEDR dataset. These approximation errors can be up to 60 m laterally and 1 m radially amid controlled spacecraft maneuvers. Furthermore, the incorporation of the updated spacecraft orbit and Mars rotational model can shift the MOLA profiles up to 200 m laterally and 0.5 m radially, which are much larger in magnitude than the aforementioned dramatic increases near the poles. However, the shifted locations of the reprocessed profiles are significantly inconsistent with the PEDR profiles after the global cross-over analysis. Full article

This work presents designed and fabricated silica few-mode optical fiber (FMF) with induced twisting 10 and 66 revolutions per meter, core diameter 11 µm, typical “telecommunication” cladding diameter 125 µm, improved height of quasi-step refractive index profile and numerical aperture 0.22. Proposed FMF supports 4 guided modes over “C”-band. We discussed selection of specified optical fiber parameters to provide desired limited mode number over mentioned wavelength range. Some results of tests, performed with pilot samples of manufactured FMF, are represented, including experimentally measured spectral responses of laser-excited optical signals, that comprise researches and analysis of few-mode effects, occurring after fiber Bragg grating writing. Full article

We herein report a simultaneous frequency stabilization of two 780-nm external cavity diode lasers using a precision wavelength meter (WLM). The laser lock performance is characterized by the Allan deviation measurement in which we find ${\sigma }_y={10}^{-12}$ at an averaging time of 1000 s. We also obtain spectral profiles through a heterodyne spectroscopy, identifying the contribution of white and flicker noises to the laser linewidth. The frequency drift of the WLM is measured to be about 2.0(4) MHz over 36 h. Utilizing the two lasers as a cooling and repumping field, we demonstrate a magneto-optical trap of ${}^{87}$Rb atoms near a high-finesse optical cavity. Our laser stabilization technique operates at broad wavelength range without a radio frequency element. Full article

Clumping index (CI) is a canopy structural variable important for modeling the terrestrial biosphere, but its retrieval from remote sensing data remains one of the least reliable. The majority of regional or global CI products available so far were generated from multiangle optical reflectance data. However, these reflectance-based estimates have well-known limitations, such as the mere use of a linear relationship between the normalized difference hotspot and darkspot (NDHD) and CI, uncertainties in bidirectional reflectance distribution function (BRDF) models used to calculate the NDHD, and coarse spatial resolutions (e.g., hundreds of meters to several kilometers). To remedy these limitations and develop alternative methods for large-scale CI mapping, here we explored the use of spaceborne lidar—the Geoscience Laser Altimeter System (GLAS)—and proposed a semi-physical algorithm to estimate CI at the footprint level. Our algorithm was formulated to leverage the full vertical canopy profile information of the GLAS full-waveform data; it converted raw waveforms to forest canopy gap distributions and gap fractions of random canopies, which was used to estimate CI based on the radiative transfer theory and a revised Beer–Lambert model. We tested our algorithm over two areas in China—the Saihanba National Forest Park and Heilongjiang Province—and assessed its relative accuracies against field-measured CI and MODIS CI products. We found that reliable estimation of CI was possible only for GLAS waveforms with high signal-to-noise ratios (e.g., >65) and at gentle slopes (e.g., <12°). Our GLAS-based CI estimates for high-quality waveforms compared well to field-based CI (i.e., R² = 0.72, RMSE = 0.07, and bias = 0.02), but they showed less correlation to MODIS CI (e.g., R² = 0.26, RMSE = 0.12, and bias = 0.04). The difference highlights the impact of the scale effect in conducting comparisons of products with huge differences resolution. Overall, our analyses represent the first attempt to use spaceborne lidar to retrieve high-resolution forest CI and our algorithm holds promise for mapping CI globally. Full article

The subject matter of the article concerns velocities/flow rate measurements in the area of disturbed flows-behind the 90° bend. They were conducted by means of an ultrasonic flowmeter with clamp-on sensors on pipeline, for water and two different Reynolds numbers of 70,000 and 100,000, corresponding to two velocities of approximately 1.42 m/s and 2.04 m/s. The tests were carried out at 12 distances from the disturbance. Sensors on the circumference of the pipeline were mounted 30° each. The correction factor values were calculated for the given measurement geometry. The measurements have shown that the values of this coefficient are always greater than 1, which means that the ultrasonic flow meter understates the speed values. They also showed that already at a distance of 8 nominal diameters from the disturbance, the correction factor does not exceed 1.02, so the measurement errors are within the maximum permissible error (MPE) of a typical ultrasonic flow meter. For distances less than eight nominal diameters from the disturbance, not taking the correction factor value into the account can lead to systematic errors of up to 10.8%. Studies have also proved that in each measurement plane behind the disturbance there are two mounting angles for the ultrasonic sensors, 60° and 240° respectively, for which the correction factor values are minimal. Additionally, using the laser Doppler anemometry (LDA) method, velocity solids were determined at individual distances from the disturbance, and the projections of velocity blocks on the appropriate plane represented velocity profiles and indicated the distances from the disturbance at which these profiles stabilise. Full article

Study Design: Surface finish of titanium patient-specific craniofacial implants is known to affect their acceptability and durability and relevant literature still inconclusive on the best surface finishing protocol. Objectives: This study investigated surface topography of three-dimensionally (3D) printed and conventionally manufactured craniofacial titanium implants following non-contact 3D laser profile-meter analysis. Methods: Seven groups of titanium specimens (n = 10) were prepared and their surfaces were treated differently and included sole or combined treatment of mechanical polishing, gritting with 50 micron AL₂O₃, cold acid treatment using nitric acid for 20 hours (70% w/w), etching using acidic solution (69% nitric and 48% hydrofluoric acids) for 10 minutes and then electro-chemically anodized in another acidic solution (85% orthophosphoric and 98%sulphuric acid). Eighth group included specimens that were 3D printed. 3D micro-roughness parameters Sa, Sp, Sv, and Sz were determined (μm) for each specimen. Data was analyzed using one way ANOVA and Dunett T3 post-hoc tests (p < 0.05). Results: There were statistically significant effects of surface finishing protocols (p < 0.05). Sa values were 2.72-13.75 and specimens which were electroplated or mechanically polished and acid treated were the smoothest (p < 0.05). Sp was in the range 9.07-43.56 as sandblasting significantly roughened surfaces (p < 0.05). The same inferior effect was evident for the Sv (p < 0.05). The Sz values were 19.46-107.05 and was the highest for sandblasted surfaces (p < 0.05) and the lowest for surfaces of electro-chemical treatment (p < 0.05). Conclusion: Titanium surfaces are affected by the finishing procedure and electro-chemical treatment or mechanical polishing combined with acid treatment produced clinically-favorable smooth surfaces. Full article

A homemade portable no-blind zone laser detection and ranging (lidar) system was designed to map the three-dimensional (3D) distribution of aerosols based on a dual-field-of-view (FOV) receiver system. This innovative lidar prototype has a space resolution of 7.5 m and a time resolution of 30 s. A blind zone of zero meters, and a transition zone of approximately 60 m were realized with careful optical alignments, and were rather meaningful to the lower atmosphere observation. With a scanning platform, the lidar system was used to locate the industrial pollution sources at ground level. The primary parameters of the transmitter, receivers, and detectors are described in this paper. Acquiring a whole return signal of this lidar system represents the key step to the retrieval of aerosol distribution with applying a linear joining method to the two FOV signals. The vertical profiles of aerosols were retrieved by the traditional Fernald method and verified by real-time observations. To effectively and reliably retrieve the horizontal distributions of aerosols, a composition of the Fernald method and the slope method were applied. In this way, a priori assumptions of even atmospheric conditions and the already-known reference point in the lidar equation were avoided. No-blind-zone vertical in-situ observation of aerosol illustrated a detailed evolution from almost 0 m to higher altitudes. No-blind-zone detection provided tiny structures of pollution distribution in lower atmosphere, which is closely related to human health. Horizontal field scanning experiments were also conducted in the Shandong Province. The results showed a high accuracy of aerosol mass movement by this lidar system. An effective quantitative way to locate pollution sources distribution was paved with the portable lidar system after validation by the mass concentration of suspended particulate matter from a ground air quality station. Full article