Scan Angle Research Articles

A Broadband and Wide-Scanning Dual-Polarized Dipole Array with Low Profile

This study presents a novel methodology for designing a planar broadband wide-scanning dual-polarized array using tightly-coupled dipoles and wide-angle impedance matching. By etching the S-shaped gaps between the dipoles and incorporating shorting vias with defected ground structures, we demonstrated that all radiation elements can be arranged on a single-layer substrate. Additionally, we introduced a thin printed circuit board (PCB) layer with two-dimensional periodic structures for impedance matching at wide scan angles. Leveraging high permittivity and constrained electromagnetic waves, we realized zero-scan blindness within this band. The aperture consisted of only two PCB layers, with a total profile of approximately 0.091λlow, where λlow represented the free-space wavelength at 6 GHz. A 3 × 4 dual-polarized array was fabricated and measured to validate the proposed approach. The measured active voltage standing wave ratio for one embedded array element surpassed 2.2 over 6–18 GHz. By enabling the orthogonal dipoles at the edge of the array to be mutually coupled using an additional metal patch, the active S11 for the edge cells exceeded −8.8 dB over 6.9–18 GHz. The measured patterns were in good agreement with simulations over 6–18 GHz, with the array exhibiting good radiation performance over ±60° in the E- and H-planes.

Leucine zipper-based SAIM imaging identifies therapeutic agents to disrupt the cancer cell glycocalyx for enhanced immunotherapy.

The abnormally thick glycocalyx of cancer cells can provide a physical barrier to immune cell recognition and effective immunotherapy. Here, we demonstrate an optical method based on Scanning Angle Interference Microscopy (SAIM) for the screening of therapeutic agents that can disrupt the glycocalyx layer as a strategy to improve anti-cancer immune responses. We developed a new membrane labeling strategy utilizing leucine zipper pairs to fluorescently mark the glycocalyx layer boundary for precise and robust measurement of glycocalyx thickness with SAIM. Using this platform, we evaluated the effects of glycosylation inhibitors and targeted enzymatic degraders of the glycocalyx, with particular focus on strategies for cholangiocarcinoma (CCA), a highly lethal malignancy with limited therapeutic options. We found that CCA had the highest mean expression of the cancer-associated mucin, MUC1, across all cancers represented in the cancer cell line encyclopedia. Pharmacological inhibitors of mucin-type O-glycosylation and mucin-specific proteases, such as StcE, could dramatically reduce the glycocalyx layer in the YSCCC model of intrahepatic CCA. Motivated by these findings, we engineered Natural Killer (NK) cells tethered with StcE to enhance NK cell-mediated cytotoxicity against CCA. In a CCA xenograft model, these engineered NK cells demonstrated superior anti-tumor efficacy compared to wild-type NK cells, with no observable adverse effects. Our findings not only provide a reliable imaging-based screening platform for evaluating glycocalyx-targeting pharmacological interventions but also offer mechanistic insights into how CCA may avoid immune elimination through fortification of the glycocalyx layer with mucins. Additionally, this work presents a novel therapeutic strategy for mucin-overexpressing cancers, potentially improving immunotherapy efficacy across various cancer types.

A 1-bit passive reconfigurable metasurface for wide-angle scanning and broad-beam reflection

ABSTRACT A reconfigurable reflective metasurface design is proposed in this letter, allowing for beam scanning capabilities. This paper integrates a tunable capacitor into the metasurface unit. This paper integrates a tunable capacitor into the metasurface unit. The resonant characteristics of the metasurface unit are controlled by the tunable capacitor, which can be adjusted by changing the rotation angle of the metal plate on the tunable capacitor. By rotating the metal plate of the capacitor, it achieves state 1 at maximum capacitance and state 0 at minimum capacitance, resulting in a phase difference of 180° ± 20° between the states, thereby enabling 1-bit phase control. Leveraging the principle of phase compensation, the phase distribution of the array is designed to exhibit directional radiation characteristics. A reflective metasurface composed of a 20 × 20-element array is designed and simulated with these characteristics. The simulation results indicate that the scanning angle of the array-reflected beam can reach ± 50°, with a peak gain exceeding 14.6 dBi, an average gain of 13.8 dBi, and a gain loss of 1.5 dB. The beam’s 3 dB beamwidth exceeds 15°, enabling broader coverage. Joint simulations in typical indoor scenarios confirm the improved signal strength, highlighting the array’s versatility. This design allows the reflective array to function as a passive reflector relay, effectively improving signal coverage in indoor NLOS.

Simultaneous Multibeam Clustered Phased Arrays Analysis Using Mixed and Multiple Antenna Element Factors.

A novel design strategy for improving the radiative performance of simultaneous multibeam (SMB) phased arrays is addressed. The proposed scheme relies on the adoption of mixed and multiple antenna element factors with a dynamic selection of their radiation patterns whose choice depends on the desired SMB pointing directions. In addition, a Penrose-inspired clustering technique is also employed for reducing the array feed points. Compared with traditional phased arrays based on a single antenna element factor, the novel array architecture allows the scan angle range to be widened by improving the minimum array gain as well as reducing the peak side lobe level (PSLL). The superior radiative performance of the proposed approach with respect to the clustered phased arrays with a single-mode element factor is assessed in SMB scenarios comprising two and three main lobe peaks. The notable SMB radiative improvement has been also confirmed from a statistical point of view by considering up to four and five concurrent main lobes. The remarkable radiative improvements confirm the effectiveness of the proposed solution, which also represents an appealing candidate for its exploitation in multiuser and multibeam communications.

Conformal leaky wave antenna based on gap waveguide technology

Abstract Due to structural and aerodynamic limitations, conformal antennas are increasingly sought after in antenna design. Gap waveguide technology has also gained traction for its potential in leaky wave antenna development. This paper proposes a novel conformal leaky wave antenna utilizing this emerging gap waveguide technology. Prior research has not extensively explored the radiation characteristics of such antennas on curved and conformal surfaces. This work addresses this gap by investigating the design procedure, radiation mechanism, and optimization methods for leaky wave antennas on conformal surfaces. The proposed antenna achieves a gain of approximately 18 dB and a scanning angle ranging from 1 to 33 degrees within the frequency band of 9.5 GHz to 12 GHz. Fabrication and subsequent measurements of the antenna were conducted, with the results demonstrating good agreement with the simulations.

Advancing Forest Plot Surveys: A Comparative Study of Visual vs. LiDAR SLAM Technologies

Forest plot surveys are vital for monitoring forest resource growth, contributing to their sustainable development. The accuracy and efficiency of these surveys are paramount, making technological advancements such as Simultaneous Localization and Mapping (SLAM) crucial. This study investigates the application of SLAM technology, utilizing LiDAR (Light Detection and Ranging) and monocular cameras, to enhance forestry plot surveys. Conducted in three 32 × 32 m plots within the Tibet Autonomous Region of China, the research compares the efficacy of LiDAR-based and visual SLAM algorithms in estimating tree parameters such as diameter at breast height (DBH), tree height, and position, alongside their adaptability to forest environments. The findings revealed that both types of algorithms achieved high precision in DBH estimation, with LiDAR SLAM presenting a root mean square error (RMSE) range of 1.4 to 1.96 cm and visual SLAM showing a slightly higher precision, with an RMSE of 0.72 to 0.85 cm. In terms of tree position accuracy, the three methods can achieve tree location measurements. LiDAR SLAM accurately represents the relative positions of trees, while the traditional and visual SLAM systems exhibit slight positional offsets for individual trees. However, discrepancies arose in tree height estimation accuracy, where visual SLAM exhibited a bias range from −0.55 to 0.19 m and an RMSE of 1.36 to 2.34 m, while LiDAR SLAM had a broader bias range and higher RMSE, especially for trees over 25 m, attributed to scanning angle limitations and branch occlusion. Moreover, the study highlights the comprehensive point cloud data generated by LiDAR SLAM, useful for calculating extensive tree parameters such as volume and carbon storage and Tree Information Modeling (TIM) through digital twin technology. In contrast, the sparser data from visual SLAM limits its use to basic parameter estimation. These insights underscore the effectiveness and precision of SLAM-based approaches in forestry plot surveys while also indicating distinct advantages and suitability of each method to different forest environments. The findings advocate for tailored survey strategies, aligning with specific forest conditions and requirements, enhancing the application of SLAM technology in forestry management and conservation efforts.

Electrostatic MEMS Two-Dimensional Scanning Micromirrors Integrated with Piezoresistive Sensors

The MEMS scanning micromirror requires angle sensors to provide real-time angle feedback during operation, ensuring a stable and accurate deflection of the micromirror. This paper proposes a method for integrating piezoresistive sensors on the torsion axis of electrostatic MEMS micromirrors to detect the deflection angle. The design uses a multi-layer bonding process to realize a vertical comb-driven structure. The device structure is designed as a double-layer structure, in which the top layer is the ground layer and integrates with piezoresistive sensor. This approach avoids crosstalk between the applied drive voltage and the piezoresistive sensor. This design also optimizes the sensor’s size, improving sensitivity. A MEMS two-dimensional (2D) scanning micromirror with a 1 mm mirror diameter was designed and fabricated. The test results indicated that, in a vacuum environment, the torsional resonance frequencies of the micromirror’s fast axis and slow axis were 17.68 kHz and 2.225 kHz, respectively. When driving voltages of 33 V and 40 V were applied to the fast axis and slow axis of the micromirror, the corresponding optical scanning angles were 55° and 45°, respectively. The piezoresistive sensor effectively detects the micromirror’s deflection state, and optimizing the sensor’s size achieved a sensitivity of 13.87 mV/V/°. The output voltage of the piezoresistive sensor shows a good linear relationship with the micromirror’s deflection angle, enabling closed-loop feedback control of the electrostatic MEMS micromirror.

Signs on glasses: LiDAR data voids, hotspot effect, and reflection artifacts

A key challenge in terrestrial laser scanning (TLS) based as-built survey is the presence of data voids, reflection artifacts, and hotspot effect on glasses. This paper investigates the effects of scanning range, illumination condition, instrument height, and spatial offset of an occluded object between the scanner and glasses with respect to these data artifacts. Experimental results show that ordinary float glass encounters a high percentage of data voids (> 93%) and reflective glass backscatters laser pulses with greater than 50%. Hotspot effect is found notable at azimuth scanning angle between ± 2 and 5° on both types of glasses. Ordinary float glass never results in any reflection artifacts, while they likely emerge when the scanner is set up at a certain height (> 0.7 m) and a closer range (≤ 7.5 m) on the reflective glass. These findings shed light on the future algorithmic development of glass detection, classification, and defects removal.

Second harmonic generation null angle polarization analysis for determining interfacial potential at charged interfaces.

Methods of quantifying the electrostatics of charged interfaces are important in a range of research areas. The surface-selective nonlinear optical technique second harmonic generation (SHG) is a sensitive probe of interfacial electrostatics. Recent work has shown that detection of the SHG phase in addition to its amplitude enables direct quantification of the interfacial potential. However, the experimental challenge of directly detecting the phase interferometrically with sufficient precision and stability has led to the proposal and development of alternative techniques to recover the same information, notably through wavelength scanning or angle scanning, each of which has their own associated experimental challenges. Here, we propose a new polarization-based approach to recover the required phase information, building upon the previously established nonlinear optical null ellipsometry (NONE) technique. Although NONE directly returns only relative phase information between different tensor elements of the second-order susceptibility, it is shown that a symmetry relation that connects the tensor elements of the potential-dependent third-order susceptibility can be used to generate the absolute phase reference required to calculate the interfacial potential. The sensitivity of the technique to potential at varying surface charge densities and ionic strengths is explored by means of simulated data of the silica:water interface. The error associated with the use of the linearized Poisson-Boltzmann approximation is discussed and compared to the error associated with the precision of the measured NONE null angles. Overall, the results suggest that NONE is a promising approach for performing phase-resolved SHG based quantification of interfacial potentials that experimentally requires only the addition of standard polarization optics to the basic single-wavelength, fixed-angle SHG apparatus.

Three-point-supported 2-DOF large-area tilting mirror inspired by a playground facility.

In this paper, we demonstrate a three-point-supported 2D optical scanner designed to enhance the field of view (FoV) and optical scanning angles, and facilitate the development of large mirrors (>10c m). By integrating fused deposition modeling (FDM) 3D printing with electromagnetic driving, we present a cost-effective, large-sized scanning mirror with two-dimensional scanning capabilities. The mirror has an area of 144c m 2, enabling greater light capture for enhanced scanning performance. Under DC driving, the maximum optical scanning angles are 5.99° in the x direction and 12.61° in the y direction. For AC driving, the resonant scanning frequencies are 18.2Hz for the x scan and 19Hz for the y scan, with maximum scanning angles of 7.87° for the x scan and 7.19° for the yscan.

A corrugated edge tapered slot dual polarized MIMO antenna for phased array systems

ABSTRACT In this paper, a corrugated-edged slot antenna with dual linear polarisation properties is presented. The antenna incorporates corrugations along the outer edges between the elements to control the complex mutual coupling effect at high scan angles, resulting in nearly linear polarised waves in the two principal E and H planes. The dual-polarised antenna structure is accomplished by incorporating two orthogonal tapered slot Vivaldi antennas in a cross-shaped configuration, ensuring there is no galvanic contact between them. The proposed four-element antenna is compact in size and has a low profile of L × W × h = 30 × 25.5 × 1 mm3. The antenna optimised dimensions have been determined through meticulous parametric studies, ensuring its suitability for operation within the desired frequency band. The proposed antenna diversity performance characteristics are analysed with regard to parameters such as envelope correlation coefficient (ECC), diversity gain (DG), mean effective gain (MEG), total active reflection coefficient (TARC) and channel capacity loss (CCL). The corresponding values obtained are 0.02, 9.97 dB, ±3 dB, −6 dB and 0.09 bits/s/Hz, respectively. To validate the design, a prototype of the four-element antenna model is fabricated and measured. The results demonstrate that the return losses (S11) are lower than −10 dB across the operational frequency band. The isolation (S21) between the antenna ports is better than -30 dB and achieved a maximum measured gain of 7.1 dB at 18 GHz.

Airborne lidar intensity correction for mapping snow cover extent and effective grain size in mountainous terrain

ABSTRACT Differentially mapping snow depth in mountain watersheds from airborne laser altimetry is a valuable hydrologic technique that has seen an expanded use in recent years. Additionally, lidar systems also record the strength of the returned light pulse (i.e. intensity), which can be used to characterize snow surface properties. For near-infrared lidar systems, return intensity is relatively high over snow and inversely related to the effective grain size, a primary control on snow albedo. Raw intensity is also sensitive to laser range and incidence angle, however, and requires a correction for snow property retrieval that is especially pertinent in mountainous terrain. Here, we describe a workflow to correct the intensity using the plane trajectory, lidar scan angle, and lidar-derived topography. As a proof of concept for snow retrievals, we apply the workflow to an airborne 1064 nm lidar flight over a snow-covered mountain basin in the Colorado Rockies. Corrected intensity was empirically related to reflectance before delineating snow extent and retrieving grain size. Relative to the traditional snow classification derived from optical imagery, the lidar-derived snow extent covered 5.4% more area due to the fine resolution point cloud and absence of shadows common in optical imagery. The lidar-derived grain size retrievals had a MAE of 32 µm compared to those from field spectroscopy, which translated to a 1% error in snow albedo. We found high incidence angles yielded an overcorrection in intensity that introduced a high bias in the grain size distribution and, therefore, suggest using an incidence angle threshold (40°). Developing methods specifically for quantitative snow surface property retrievals from lidar intensity is timely and relevant as aerial lidar is increasingly being used to map snow depth for hydrologic and cryospheric studies.

Hybrid siloxane oligomer: A promising consolidant for the conservation of powdered tremolite jade artifacts

Jade has played a pivotal role in the political, economic, cultural, and technological development of ancient societies. However, numerous tremolite jade artifacts unearthed from archaeological sites exhibit various deterioration patterns due to natural weathering and human activities. Among these, powdering is the most detrimental form of degradation, significantly affecting the physical characteristics of artifacts, as well as archaeological research and museum exhibitions. This paper develops a novel hybrid siloxane oligomer as a potential consolidant for powdered tremolite jade artifacts and compares it with traditional consolidants, including acrylic resin and ethyl silicate. Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and X-ray fluorescence (XRF) analyses show that the jade samples used in the experiment are predominantly composed of tremolite. Various techniques are employed to evaluate and compare the effectiveness of the three consolidants, including color variation tests, open porosity tests, contact angle measurements, peeling tests, hardness tests, ultra-depth-of-field microscopy, and scanning electron microscopy (SEM). The novel hybrid siloxane oligomer demonstrates superior consolidation effects, with consolidated samples showing significant improvements in mechanical properties, reaching a Leeb hardness of 163 HL, while maintaining color variations within acceptable limits (ΔE = 3.87). The results demonstrate the potential of the novel hybrid siloxane oligomer in consolidating powdered tremolite jade artifacts.

Mechanism of selective texturing of CFRP by femtosecond laser

Carbon fiber-reinforced polymer (CFRP) has become an indispensable key material in the aerospace field due to its advantages of lightweight and high strength. In this study, a new process of selective texturing by femtosecond laser is proposed to improve the surface performance of CFRP without destroying fiber continuity. To explore the process mechanism of selective texturing of CFRP, the concept of the removal threshold is proposed, the influence of laser scanning direction and laser energy on the groove and the HAZ is studied. Furthermore, the optimization strategy of processing parameters during selective texturing is given. It is found that the scanning direction influences the transfer path of the heat significantly and therefore affects the groove geometry. As the scanning angle increases, the ablation threshold of resin rises gradually, while the ablation threshold of carbon fiber experiences a rapid increase before 30° and a gentle increase thereafter. Additionally, the groove shows a steady growth in width and undergoes a stepped decrease in depth, and the width of the HAZ increases. As laser energy increases, the width of the groove and HAZ increases, and the depth of the groove increases in a step pattern. The selective texturing mechanism of surface resin involves the coupling superposition of multiple effects, including photolysis resulting from multi-photon absorption, pyrolysis caused by direct laser energy absorption, thermal effects due to heat transfer of fiber, thermal effects of pyrolysis gas, and mechanical denudation. The laser energy density of 12-13J/cm2 is the optimal parameter range for achieving selective texturing.

Линейная фазированная решётка печатных дипольных антенн с емкостным питанием для системы связи 5G мм-диапазона длин волн

The paper presents the design of a previously developed capacitive feed printed dipole array element. A comparison of its frequency characteristics of the VSWR as part of an infinite antenna array and as part of a 4 × 4 broadside antenna array is shown. In the frequency range from 25 to 26 GHz, the VSWR of the infinite array element did not exceed 1.3, and for the finite array does not exceed 1.6 (for the central elements is 1.5)). The aim of this work was to develop a linear phased array antenna based on a previously developed element and to evaluate the stability of its VSWR frequency characteristics. An 8-element linear phased array with scanning in the H-plane in the ±45° angle sector was developed. All but the edge elements have good repeatability of the characteristics (the spread of values does not exceed 0.10 for the VSWR ≤ 1.5 and 0.15 for the other values of the VSWR). At the same time, in the range from 25 to 26 GHz, in the broadside, the values of VSWR ≤ 1.42 and VSWR ≤ 2.06 are at a scanning angle equal to ± 45 °. The isolation between array elements is no more than -17.5 dB.

3D Light-Direction Sensor Based on Segmented Concentric Nanorings Combined with Deep Learning.

High-precision, ultra-thin angular detectable imaging upon a single pixel holds significant promise for light-field detection and reconstruction, thereby catalyzing advancements in machine vision and interaction technology. Traditional light-direction angle sensors relying on optical components like gratings and lenses face inherent constraints from diffraction limits in achieving device miniaturization. Recently, angle sensors via coupled double nanowires have demonstrated prowess in attaining high-precision angle perception of incident light at sub-wavelength device scales, which may herald a novel design paradigm for ultra-compact angle sensors. However, the current approach to measuring the three-dimensional (3D) incident light direction is unstable. In this paper, we propose a sensor concept capable of discerning the 3D light-direction based on a segmented concentric nanoring structure that is sensitive to both elevation angle (θ) and azimuth angle (ϕ) at a micrometer device scale and is validated through simulations. Through deep learning (DL) analysis and prediction, our simulations reveal that for angle scanning with a step size of 1°, the device can still achieve a detection range of 0∼360° for ϕ and 45°∼90° for θ, with an average accuracy of 0.19°, and DL can further solve some data aliasing problems to expand the sensing range. Our design broadens the angle sensing dimension based on mutual resonance coupling among nanoring segments, and through waveguide implementation or sensor array arrangements, the detection range can be flexibly adjusted to accommodate diverse application scenarios.

Synergistic impact of scan strategy and scan angles in laser powder bed fusion process on mechanical, tribological and cell viability properties of porous 316L SS structure

Poor load bearing ability and concentrated stress within cross-linked porous structures was found to be the major cause for the mechanical and wear failure of SS (Stainless Steel) 316L implants. Therefore, the present study introduces a novel scan pattern to enhance the mechanical and wear properties. Importantly, the role of porous structures on the constituents and formation of Tribo-film regimes under the simulated body fluid (SBF) condition were assessed using the X-ray photoelectron spectroscopy (XPS). Furthermore, the impact of the surface roughness of porous structures on the cell adhesion and cytotoxicity were explored. Various cross-linked porous structures are produced at three different scanning rotation angles (0°, 45°, and 90°) using the Laser powder bed fusion (LPBF) process. Morphology analysis reveals balling and stair-case effects at 0°, controlled for structures built at 45° and 90°. Porous-90° structure exhibits negative skewness and a platykurtic surface with low peaks and more valleys. It demonstrates higher strength with low density due to better particle fusion, net-like structure, and uniform element distribution. X-ray photoelectron spectroscopy (XPS) evaluates the impact of porous structures on Tribo-film regimes in simulated body fluid. Surface roughness effects on cell adhesion and cytotoxicity are also investigated. Cross linked porous structures presented two major compression failure modes include wrinkling and diagonal shearing. The densified structure of Porous-45° reduces contamination and cell death, facilitating stable cell growth. Tribo-film formation and load bearing ability of Porous-90° structure was better than the other structures, due to the cross-linked netlike structure and further more detailed in the XPS study.

Design of bi-axial piezoelectric MEMS micro mirror with gimbal actuator for dynamic decoupling

Abstract This study presents a novel structural design of a bi-axial piezoelectric micro-electro-mechanical-systems scanning mirror aimed at preventing the dynamic coupling between the two scanning axes and avoiding distortion of the scanning pattern. In the proposed design, the gimbal actuator, constrained by torsional springs at both ends, not only serves as the torque generation component for the actuation of one axis but also acts as a pivot to prevent structural interference between the two axes during scanning. This approach achieves the advantages of decoupling and compactness simultaneously. Simulations indicate that the gimbal actuator experiences very small displacement during y-axis actuation, thus realizing the dynamic decoupling from the x-axis scanning unit. To evaluate the proposed designs, fabrication processes were adopted on a silicon-on-insulator wafer with a lead zirconium titanate film. The miniaturized scanners, featuring a mirror with a 1.2 mm diameter, were realized on a compact 5 × 5 mm2 chip. Measurements indicate that the resonant frequencies of x-axis and y-axis scanning are 2.69 kHz and 4.29 kHz, respectively, and the optical scanning angles reach 33° and 21° under an 8 Vpp driving voltage. Additionally, measurements show that the displacement ratio between the central mirror and the gimbal actuator can reach up to 17 during y-axis actuation, verifying the concept of dynamic decoupling. The bi-axial Lissajous scanning pattern with straight edges also demonstrates the effective decoupling by the proposed gimbal actuator design.

DMD and microlens array as a switchable module for illumination angle scanning in optical diffraction tomography.

Optical diffraction tomography (ODT) enables label-free and morphological 3D imaging of biological samples using refractive-index (RI) contrast. To accomplish this, ODT systems typically capture multiple angular-specific scattering measurements, which are used to computationally reconstruct a sample's 3D RI. Standard ODT systems employ scanning mirrors to generate angular illuminations. However, scanning mirrors are limited to illuminating the sample from only one angle at a time. Furthermore, when operated at high speeds, these mirrors may exhibit mechanical instabilities that compromise image quality and measurement speed. Recently, newer ODT systems have been introduced that utilize digital-micromirror devices (DMD), spatial light modulators (SLMs), or LED arrays to achieve switchable angle-scanning with no physically-scanning components. However, these systems associate with power inefficiencies and/or spurious diffraction orders that can also limit imaging performance. In this work, we developed a novel non-interferometric ODT system that utilizes a fully switchable module for angle scanning composed of a DMD and microlens array (MLA). Compared to other switchable ODT systems, this module enables each illumination angle to be generated fully independently from every other illumination angle (i.e., no spurious diffraction orders) while also optimizing the power efficiency based on the required density of illumination angles. We validate the quantitative imaging capability of this system using calibration microspheres. We also demonstrate its capability for imaging multiple-scattering samples by imaging an early-stage zebrafish embryo.

The effect of polylactic acid ordering on the long-term corrosion protection capacity of biodegradable magnesium alloys

The polylactic acid (PLA) coatings of different crystallinity were prepared on biodegradable Mg-2.2Zn-0.3Ca alloy wires to improve the long-term anti-corrosion properties. The composition characteristics and microstructure of the samples were investigated by differential scanning calorimetry (DSC), Fourier transform infrared spectroscope (FTIR), wide angle X-ray diffraction (WAXD) and scanning electron microscope (SEM). The corrosion resistance of all samples was investigated by immersion tests and electrochemical techniques in vitro simulated body fluid (SBF). The results indicated heat treatment improved the crystallinity of PLA coating and heated-coating performed protective behaviors in the short and long-term immersion. The corrosion rate of heated samples was lower than that of unheated samples and exhibited superior long term protective effect for Mg alloy wires. The lifetime of heated sample (H2) increased significantly from 33 to 55 days. The initial electrochemical performance of unheated coating was better than heated coating, but it declined more rapidly during the long-term immersion. These results indicated that PLA coating could not ignore the effect of its crystallinity to anti-corrosion ability, and only the suit heat treatment makes PLA coating more ordering and achieves higher corrosion resistance in vitro immersion. Therefore, it has promising potential by controlling effectively the PLA ordering for surgical implant applications.