Freeform optical surfaces are advantageous to optical designers, as they provide additional degrees of freedom for optimization. The loss of rotational symmetry, however, makes measurement of ...freeforms more challenging. Herein, advances in interferometric areal measurement of freeform optical surfaces, including null tests, non‐null tests, near‐null tests, and adaptive null tests, are reviewed. Some new developments, in the Hartmann test, deflectometry, and phase retrieval, as representatives of non‐interferometric areal measurement, are then presented. Overall, the focus is on single‐point‐probe‐based profilometry categorized into coordinate measurements and slope‐ or curvature‐based measurements. Innovative measurement technology is trying to bridge the gap between high accuracy and high dynamic range as freeform optical surfaces are finding more applications in visible and shorter‐wavelength optics.
Freeform optical surfaces featuring loss of rotational symmetry call for innovation of measurement technology. A comprehensive review is presented on measurement methods categorized into interferometric areal measurement, non‐interferometric areal measurement, and single‐point‐probe‐based profilometry. There are around 20 methods reviewed in total, with a focus on the achievable accuracy and dynamic range, as well as commercial availability.
Abstract
Artificial photosynthesis is a promising strategy for efficient hydrogen peroxide production, but the poor directional charge transfer from bulk to active sites restricts the overall ...photocatalytic efficiency. To address this, a new process of dipole field-driven spontaneous polarization in nitrogen-rich triazole-based carbon nitride (C
3
N
5
) to harness photogenerated charge kinetics for hydrogen peroxide production is constructed. Here, C
3
N
5
achieves a hydrogen peroxide photosynthesis rate of 3809.5 µmol g
−1
h
−1
and a 2e
−
transfer selectivity of 92% under simulated sunlight and ultrasonic forces. This high performance is attributed to the introduction of rich nitrogen active sites of the triazole ring in C
3
N
5
, which brings a dipole field. This dipole field induces a spontaneous polarization field to accelerate a rapid directional electron transfer process to nitrogen active sites and therefore induces Pauling-type adsorption of oxygen through an indirect 2e
−
transfer pathway to form hydrogen peroxide. This innovative concept using a dipole field to harness the migration and transport of photogenerated carriers provides a new route to improve photosynthesis efficiency via structural engineering.
Mesoporous carbon with high mesoporosity could overcome the diffusion limitations in the application fields requiring fast mass transportation. However, traditional templating approaches-derived ...carbons usually own low mesoporosity resulted from the microporosity dominated nanostructure. Herein, we developed a versatile method adopting self-made Fe(OH)
3
as coordinative template to absorb phenols by coordination effect and in situ inducing the polymerization of phenol and formaldehyde to form phenolic resin at Fe(OH)
3
. Then, the generated H
2
O and the derived iron oxide from the template upon high temperature could serve as activation regents and mold constructing rich mesoporosity and graphitic structure. The derived products possess foam-like morphology, worm-like mesoporous structure, good graphitization degree, large surface area (1590 m
2
/g), large pore volume (2.86 cm
3
/g), uniform pore size distribution (~ 3.1 nm), ultrahigh mesoporosity (98.6%) and exhibit an excellent energy storage performance for aqueous supercapacitor including large energy density of 30.6 Wh/kg, superior capacitance retention of 76.8% and long cycling stability with near 100% capacitance retention after 10 000 cycles at large current density of 20 A/g. The superior capacitance retention for SC implies a wide application potentiality of the developed mesoporous carbon in other fields closely related to fast mass transfer such as catalysis, sorption and so on.
Graphical abstract
Most of magnesium matrix composites processed by traditional technique have poor anti-corrosion and biological performance, because of uneven microstructure, especially for nonuniform distribution of ...reinforced particles. Friction stir processing (FSP) can be used for preparing magnesium matrix composites with refine grains and uniform distribution of reinforced particles. In this paper, multi-pass FSP is employed to fabricate the ZrO2 particles reinforced AZ31 magnesium composites. The results showed that the microstructure of the composites become more homogeneous with the increase of FSP pass. The grain size is refined from 10 μm of basal metal (BM) to 8.2 μm of two-pass FSP (FSP-2P) and 4.5 μm of four-pass FSP (FSP-4P), respectively. The ultimate tensile strength, yield strength and elongation of BM is 283 MPa, 137 MPa and 15.5%. The mechanical properties are improved with the increase of FSP pass. The ultimate tensile strength, yield strength and elongation of FSP-4P is 328 MPa, 160 MPa, and 11.5%, respectively. Moreover, the corrosion resistance is arranged in the following order: FSP-2P < BM < FSP-4P. The cell activity of FSP-4P is higher than that of FSP-2P sample, which is similar to BM.
Limited by the aperture and f/number of the transmission sphere (TS), large convex spheres with very small R/number (ratio of the radius of curvature to the aperture) cannot be tested in a single ...measurement with a standard interferometer. We present the algorithm and troubleshooting for subaperture stitching test of a half meter-class convex sphere with R/0.61. Totally 90 off-axis subapertures are arranged on 5 rings around the central one. Since the subaperture is so small, its surface error is comparable with that of the TS reference error. Hence a self-calibrated stitching algorithm is proposed to separate the reference error from the measurements. Another serious problem is the nonlinear mapping between the subaperture's local coordinates and the full aperture's global coordinates. The nonlinearity increases remarkably with the off-axis angle. As a result, we cannot directly remove power from the full aperture error map as we usually do. Otherwise incorrect spherical aberration will be generated. We therefore propose the sphericity assessment algorithm to match the stitched surface error with a best-fit sphere. The residual is true surface error which can be used for corrective figuring or for tolerance assessment. The self-calibrated stitching and troubleshooting are demonstrated experimentally.
In this work, a novel phenanthro9,10-dimidazole-zinc coordination complex (Zn(TPPI)
2
) is reported. This compound exhibits suitable physical properties for a host material. First, its highest ...occupied molecular orbital (HOMO) (− 5.33 eV) energy level is favorable for hole injection from transporting layer. Second, its small singlet–triplet splitting (0.31 eV) can reduce the intrinsic energy loss from singlet to triplet excited state and promote the device efficiency. Finally, its good thermal stability (decomposition temperature: 495 °C) favors evaporation preparation of uniform films. As a result, yellow–red and red phosphorescent devices which utilize Zn(TPPI)
2
as host display high efficiencies (yellow–red: 58.35 cd/A, 70.52 lm/W, 20.82%) (red: 15.89 cd/A, 16.09 lm/W and 19.05%). The performance of red device is comparable to the best results of previous publications on corresponding emitter. Meanwhile, the undoped device of Zn(TPPI)
2
exhibits high efficiencies (3.79 cd/A, 3.97 lm/W, 2.47%) in zinc-complex blue emitters. These results demonstrate that Zn(TPPI)
2
is a good blue emitter and host material.
Nitrate (NO
) pollution poses significant threats to water quality and global nitrogen cycles. Alkaline electrocatalytic NO
reduction reaction (NO
RR) emerges as an attractive route for enabling NO
...removal and sustainable ammonia (NH
) synthesis. However, it suffers from insufficient proton (H
) supply in high pH conditions, restricting NO
-to-NH
activity. Herein, we propose a halogen-mediated H
feeding strategy to enhance the alkaline NO
RR performance. Our platform achieves near-100% NH
Faradaic efficiency (pH = 14) with a current density of 2 A cm
and enables an over 99% NO
-to-NH
conversion efficiency. We also convert NO
to high-purity NH
Cl with near-unity efficiency, suggesting a practical approach to valorizing pollutants into valuable ammonia products. Theoretical simulations and in situ experiments reveal that Cl-coordination endows a shifted d-band center of Pd atoms to construct local H
-abundant environments, through arousing dangling O-H water dissociation and fast *H desorption, for *NO intermediate hydrogenation and finally effective NO
-to-NH
conversion.
Because of its high sensitivity to misalignment, precision grinding of free-form surfaces with micron accuracy requires accurate registration of the surface measurement point cloud. Registration of ...point clouds obtained with a coordinate measuring machine (CMM) is generally an iterative process of finding optimal coordinate transformation between the CMM frame and the model frame of the workpiece by minimizing the point-to-surface distances with probe radius compensation. For free-form surfaces, frequent calculation of point-to-surface distances consumes very much time, and a trade-off has to be made between the efficiency and the accuracy. This paper presents a method for fast registration of free-form surface point clouds based on the point-to-triangle distance which involves only Delaunay triangulation of a two-dimensional dataset, and the surface normal is quickly calculated from cross product. Probe radius compensation is realized by registering the probe center points with the offset surface. We prove that it is equivalent to registering the probe contact points with the nominal surface through theoretical analysis. The registration problem is then formulated as sequential linear least-square problems with properly defined ball constraints. To validate the method, numerical simulations are presented to show the accuracy of the point-to-triangle distance. The registration algorithm also shows excellent robustness against misalignment of tens of millimeters/degrees. Finally measurement, registration, and grinding of a free-form optical surface are experimentally demonstrated. The surface error obtained after registration is used for compensatory grinding which reduces it to micron level.
In this paper, porphyrin-based cationic conjugated network (PCCN) nanosheets were synthesized, and its adsorption for TcO
4
−
/ReO
4
−
was investigated. This material was stacked with AB dislocation, ...with an aperture of 1.2 nm. The Re(VII)/Tc(VII) adsorption kinetics of PCCN is extremely fast, and the adsorption capacity is relatively large, the selective order is ReO
4
−
> NO
3
−
> Cl
−
. XPS and DFT revealed that the exchange of Cl
−
on PCCN with ReO
4
−
, while the hydrophobic pore of PCCN are the keys to improve adsorption selectivity. It could be used to remove Tc from groundwater around nuclear facilities.
Graphic abstract
Molybdenum (Mo) doped BiVO₄ was fabricated via a simple electrospun method. Morphology, structure, chemical states and optical properties of the obtained catalysts were characterized by X-ray ...diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), N₂ adsorption-desorption isotherms (BET) and photoluminescence spectrum (PL), respectively. The photocatalytic properties indicate that doping Mo into BiVO₄ can enhance the photocatalytic activity and dark adsorption ability. The photocatalytic test suggests that the 1% Mo-BiVO₄ shows the best photocatalytic activity, which is about three times higher than pure BiVO₄. Meanwhile, 3% Mo-BiVO₄ shows stronger dark adsorption than pure BiVO₄ and 1% Mo-BiVO₄. The enhancement in photocatalytic property should be ascribed to that BiVO₄ with small amount of Mo doping could efficiently separate the photogenerated carries and improve the electronic conductivity. The high concentration doping would lead the crystal structure transformation from monoclinic to tetragonal phase, as well as the formation of MoO₃ nanoparticles on the BiVO₄ surface, which could also act as recombination centers to decrease the photocatalytic activity.
PDF
![Novel phenanthro[9,10-d]imi...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0957-4522/small "Novel phenanthro[9,10-d]imidazole-zinc complex as a host for high-performance OLEDs")
