Search

[Display omitted] • Ni electron depletion on NiPc/CNTs is alleviated by doping electron-deficient B. • Ni site in NiPc/B-CNTs is electron-enriched state, lowering CO 2 RR reaction barrier. • The NiPc/B-CNTs presents prominent CO 2 RR performance in neutral electrolytes. Dispersed nickel phthalocyanine (NiPc) on carbon nanotubes (CNTs) is the promising electrocatalyst for carbon dioxide reduction (CO 2 RR), but the strong interfacial electron interaction causes Ni electron depletion, limiting CO 2 RR performance. Herein, engineering the heteroatom doping in CNTs is proposed to alleviate electron depletion of Ni sites toward effective CO 2 RR. Boron heteroatoms induce electron-enriched Ni sites in NiPc/B-CNTs compared to phosphorus, nitrogen, and fluorine doped catalysts, resulting in superior CO 2 RR performance. Impressively, the NiPc/B-CNTs presents high CO Faraday efficiency (FE CO) of >98 % from −20 to −80 mA cm−2 and excellent stability up to 37 h with sustained FE CO of > 90 % in neutral electrolyte. Theoretical and experimental investigation reveals that implanting B heteroatoms alleviates Ni electron depletion via weakening electron transfer from NiPc to CNTs and thus reduces reaction barrier of *COOH formation, facilitating CO 2 RR. This study highlights importance of modifying carbon substrate in development of supported molecular catalysts for practical applications. [ABSTRACT FROM AUTHOR]

• Monolithic multiple surfaces simplifies the alignment by "freezing" surfaces. • Multiple surfaces including form and orientation are measured simultaneously by a single CGH. • Null test is used as feedback after mapping distortion correction. • Higher accuracy is achieved by corrective machining with fast axis servo. • Null fringes are experimentally observed for monolithic two mirrors in final test. Monolithic multiple freeform mirrors integrate two or more surfaces on a single substrate. Alignment of these surfaces is no longer required because they are frozen there as they are machined. Null test is then critical as a feedback to corrective machining which is indispensable for high accuracy optics. This paper presents a methodology for corrective machining of monolithic multiple freeform mirrors based on holographic null test capable of measuring multiple surfaces simultaneously. The surfaces are firstly related and modeled by coordinate transformation. A single computer generated hologram is then proposed with different regions to compensate aberrations of different surfaces. A combined tilt and power carrier is designed to separate the disturbance orders of diffraction. Mapping distortion in the null test is corrected through a pure ray tracing procedure by introducing a virtual reference sphere. The surface error including the orientation error is then superposed on the nominal surface to generate the tool path for corrective machining with fast axis servo. The tool radius and decenter is recognized by pre-cutting a spherical surface. The remounted workpiece is aligned with the machine tool by using an on-machine probe. Finally the proposed method is experimentally verified by corrective machining monolithic two mirrors with surface error effectively reduced and null fringes observed for both surfaces. [ABSTRACT FROM AUTHOR]

Highlights • We present a novel flatness test which only using two flats. • Multi-shift and rotation steps are needed. • A pixel level spatial resolution can be achieved. • Analysis to tilt error and rotation error is presented. • Simulations and experimental absolute results are given. Abstract In classical three-flat test, error in reference surface can not be identified fully. What we obtain is only the absolute radial profile instead. In addition, at least three flats with similarly high accuracy are required. The test procedures are very complex and it takes a long time and requires high precision adjustment. In this paper, we proposed a new method for absolute test of flatness. There are only two flats used in our method and it does not need precise alignment of the specimens. The method requires multiple translations of the test surface and one 90° rotation step. The relative tilt during translation is measured by a compact wavefront interferometer. We analyze the effect of noise, tilt estimation error and rotation error on reconstruction result. The method is experimentally verified and compared with the direct interferometric result using high precision reference surface. [ABSTRACT FROM AUTHOR]

In traditional three flat test, it only provides the absolute profile along one surface diameter. In this paper, an absolute testing algorithm based on shift-rotation with three flat test has been proposed to reconstruct two-dimensional surface exactly. Pitch and yaw error during shift procedure is analyzed and compensated in our method. Compared with multi-rotation method proposed before, it only needs a 90° rotation and a shift, which is easy to carry out especially in condition of large size surface. It allows pixel level spatial resolution to be achieved without interpolation or assumption to the test surface. In addition, numerical simulations and optical tests are implemented and show the high accuracy recovery capability of the proposed method. [ABSTRACT FROM AUTHOR]

Interferometric test of large convex aspheres with high accuracy is still an urgent problem. Adopting a large-aperture null corrector is usually inevitable, and it is imperative to certify the large-aperture null optics in case incorrect final shape of the aspheric mirror is obtained. Moreover, it is necessary to calibrate and remove errors of the large-aperture null lens and trace errors to surfaces that are easy to obtain high accuracy. For these purpose, this paper presents an in situ calibrated null test method. The large-aperture null corrector for convex aspheric mirror is verified and calibrated by a wisely designed small aperture certifying null whose surfaces are either flat or spherical which are easy to be fabricated, measured and assembled. A redundant test is implemented by a Zygo VeriFire Asphere interferometer for cross test. Compared with existing methods of certificating null correctors which utilize an expensive CGH or a self-aligning aspherical mirror, the presented method finally traces errors of a large-aperture null corrector to small aperture flat and spherical surfaces thus costs are expected to be saved dramatically. [ABSTRACT FROM AUTHOR]

Silver nanowire (AgNW) ink has great influence on the performance of the resulting AgNW-based conductive film, especially for the large-scale roll-to-roll processed films. However, AgNW inks made by researchers are almost immature because there is not a clear research procedure for the development of qualified inks. In this work, electric double layer model, Young equation, bubble theory, percolation theory, Rhodes & Orchäd equation, Kelvin equation and other theoretical models were introduced successively to describe those processes which additives in inks should adjust. Based on the guidance of these theories, additives were determined successively and an optimized light grey ink with the composition of 0.4% AgNW + 0.2% 2-amino-2-methyl-1-propanol + 0.01% Zonyl FSO-100 + 1.5% diacetone alcohol + 5% 1,4-dioxane + 92.89% isopropyl alcohol was obtained. Except for trace amount of Zonyl FSO-100, other additives could be easily eliminated at low temperature (110 °C), which could retain the original properties of AgNW furthest and greatly lower the dosage of AgNW in inks. Based on this ink, excellent AgNW/PET composite film was prepared. The sheet resistance, transmittance and haze of this film were 29.5 Ω/sq, 88.9% and 1.49% respectively. Finally, touch screens (180 mm × 105 mm) and tablets (10 inches) were prepared from our films and showed good performance. These results demonstrated that excellent AgNW ink could be developed through our research procedure. Our studies not only produce an excellent AgNW ink, but also provide a systematic research procedure and series of theoretical models for many kinds of conductive inks. [ABSTRACT FROM AUTHOR]

Subaperture stitching test in combination of the reconfigurable optical null we proposed recently provides flexible solutions to various surfaces including convex aspheres and even aspheres of large aperture. However it is challenging for the stitching optimization to get the real surface error because the surface error is strongly coupled with misalignment-induced aberrations in near-null subaperture measurements. Aiming at this challenge, we first figure out the property of aberrations induced by misalignment of optical null or test surface. It shows that identical misalignment of the optical null introduces nearly identical aberrations to subapertures with different off-axis distances, while misalignment of the test surface introduces little aberrations to the central subaperture. The stitching algorithm is then proposed with focus on decoupling surface error and induced aberrations. The major step is to calibrate out the effect of misaligned near-null optics before stitching optimization by using the central subaperture measurement. We also present the through-the-back null test for the purpose of cross test. The axial distance is precisely monitored by a low coherence interferometer, which enables accurate determination of the spherical aberration component of surface error. Final experimental results show consistent spherical aberration obtained by stitching test and by the through-the-back null test. It is a big step towards instrumentation of subaperture stitching test for aspheres with rather big amount of misalignments in surface metrology practice. [ABSTRACT FROM AUTHOR]

A diphenylamino-substituted bicarbazole derivative (BCZDA) with high glass-transition temperature (170 °C) has been developed. The introduction of the strongly electron-donating diphenylamino group endows this compound with high HOMO (−4.94 eV), LUMO (−1.94 eV) and triplet energy (2.65 eV) levels which are beneficial for hole injection and electron/triplet exciton blocking. By adopting this compound as the hole-transporting layer, both fluorescent and phosphorescent devices with good performance have been realized. Through the device study, the performance of this compound is proved to be comparable to that of NPB. The utility of this compound as a host has also been evaluated. [ABSTRACT FROM AUTHOR]

• Multi-scale measurement of DOEs based on stitching interference microscopy. • Inherited advantages of high resolution and high accuracy. • Extended lateral range of measurement to 10 mm scale via subaperture stitching. • Simultaneous correction of 6-dof scanning motion error for seamless data fusion. • Full aperture fabrication error map obtained with undercut effect verification. The development of diffractive optical elements (DOEs)enables fascinatingly compact design and chromatic aberration correction. Fabrication errors of DOEs include periodic pattern error, relief profile error and roughness which affect imaging quality and diffraction efficiency. Characterization of the DOE requires thus multi-scale measurement of the surface topography over the full aperture of 10 mm scale. This paper presents a method based on the white light interferometry in combination of subaperture stitching. Firstly, the principle of measurement and subaperture layout design is introduced. The measuring system is easily set up by integrating a scanning platform with the interference microscope. Subaperture stitching algorithm is developed based on the surface height change related to the scanning motion error. The slope of the relief profile is used to model the deviations of overlapping point pairs induced by lateral shift and rotation. Finally, the topography and fabrication error of a Fresnel lens surface are experimentally obtained and characterized over the full aperture through stitching of totally 67 subapertures. [ABSTRACT FROM AUTHOR]

Aiming to develop a prototype swing arm profilometer for several meter-class aspheres, we first present detailed error analysis including error motions of the swing rotary table and the part rotary table, and misalignment of the axes of the two rotary tables. The induced probing error in the normal direction of the reference sphere is calculated by considering the error motions in the coordinate transformation. A surface reconstruction algorithm is then proposed to separate the error motions of the part rotary table by stitching multiple traces. The error motions are optimally recognized and then removed from the trace measurement based on the least squares principle. We model the objective function by relating the normal error to the rigid body transformation of each trace. The basic idea is to minimize the inconsistency of all intersection points of different traces simultaneously. Finally the algorithm is verified through simulations. It shows that error motions of sub-milliradian scale are even tolerant with the surface reconstruction algorithm. [ABSTRACT FROM AUTHOR]

In this work, a novel deep-red (642 nm) iridium complex, Ir(bp4b) 2 (dend), is developed. The introduction of alkyl groups in ligands weakens the intermolecular interactions and endows Ir(bp4b) 2 (dend) with favorable physical properties: short photoluminescence lifetime (271.6 ns), low concentration sensitivity (10−6 to 10−4 M) and balanced charge-transporting ability. Ir(bp4b) 2 (dend)-doped phosphorescent device displays high efficiencies (9.62 cd/A, 12.25 lm/W, 15.29%), low roll-off of efficiencies (from 10 to 1000 cd/m2: no decrease; from 1000 to 5000 cd/m2: 10.6%), relatively low concentration sensitivity (from 5% to 15%), long device lifetime (T 80 : 5225 h at 100 cd/m2) and very stable electroluminescent spectra (from 1 cd/m2 to maximum luminance). This performance is comparable to those of previous record deep-red (around 640 nm) phosphorescent emitters. More importantly, compared with previous record emitters, Ir(bp4b) 2 (dend) reports more kinds of excellent parameters and such comprehensive deep-red emitter is rare at present. [Display omitted] • A novel deep-red (642 nm) iridium complex with favorable physical properties is developed. • Ir(bp4b) 2 (dend)-doped phosphorescent device displays high and comprehensive performance. • This device performance is comparable to those of previous record deep-red (around 640 nm) phosphorescent emitters. [ABSTRACT FROM AUTHOR]

• Optical surface metrology based on stitching interference microscopy. • Flexible adaptability to sophisticated variation of the aspheric surface shape. • "One-stop" measurement of surface form, waviness and roughness simultaneously. • Applied to even asphere, "gull-wing" surface and microstructured curved surface. • Verified with CGH null test and stylus profilometry for 10 mm-class optics. Small optics of 10 mm-scale are widely used in miniature cameras with increasingly sophisticated surface shape. The surface features ranging from low to high frequency need to be measured efficiently for in-process quality control. Wavefront interferometry is applicable with specifically designed null optics for each surface, but not preferred for small optics because the surface radius is approaching the shortest measurable radius limited by the interferometer optics. We present a strategy for flexible surface metrology based on stitching interference microscopy. The full aperture surface is divided into a series of small subapertures with reduced size and slope which are then measurable with a standard interference microscope. The measurement principle is introduced and a method for subaperture design is proposed by checking the subaperture size and slope after coordinate transformation. A simultaneous stitching algorithm is proposed to minimize the overlapping deviations with overlapping points and subaperture configurations determined automatically in a way of alternating optimization. Instrumentation is easy by integrating a multi-axis platform with a commercial interference microscope. Both the lateral and the vertical scales need to be calibrated to give accurate subaperture measurement of three coordinates. The capability of the instrument is finally verified through a series of experiments compared with cross tests such as the null test and the stylus profilometry. It shows high flexibility to measure a variety of complex surfaces including the high-order even asphere, the "gull-wing" surface and microstructured curved surfaces without using any auxiliary null optics. The instrument enables "one-stop" measurement of surface form, waviness and roughness simultaneously. [ABSTRACT FROM AUTHOR]

Abstract: Subaperture stitching interferometry combined with a test plate is attractive for testing large convex aspheres, but the stitching algorithm is challenging because the aberrations induced by misaligned test surface or test plate are coupled with the surface figure. By relating the subaperture configuration to the overlapping deviations through ray trace and coordinate transformation, the subaperture misalignment is optimally recognized and corrected to give a minimal overlapping inconsistency in an iterative way. Allowing for misaligned test plate, we decompose the induced aberrations into three parts which are corrected by the stitching algorithm, removed in the form of the Zernike polynomials and left uncorrected as residuals. Finally we present simulation results of testing a convex aspheric mirror with a computer generated hologram which shows the algorithm successfully retrieves the surface figure with the test mirror or the hologram misaligned. [Copyright &y& Elsevier]

Abstract: Stitching test of large optical flats is still quite challenging. In this paper, aiming to reduce the 2nd order error accumulation effect, separation of the reference surface error from the subaperture measurements is proposed in stitching of large flats. The reference error is decomposed into power and astigmatism, residual Zernike polynomial surface and high frequency component, which are estimated or calibrated, respectively. The error separation procedure is then incorporated into the subaperture stitching algorithm. Finally experiments are presented to show the effect of error reductions in stitching test of a 600mm-aperture flat, with reference surface separated and verified by the factory report of the transmission flat. [Copyright &y& Elsevier]

• Measurement of large area micro topography with subaperture stitching. • Detection of edge features with slope threshold and projection on OXY plane. • Fast correction of 2D lateral coordinates by solving a linear least-squares. • Correction of height coordinates by solving a linear least-squares problem. • No need for high precision scanning stages with "sliding" eliminated by stitching. Microstructured surfaces over large areas are typical in diffractive optics and biomimetic surfaces. The topography measurement is challenging due to the multi-scale nature. In this paper, an efficient stitching method is proposed for fusion of multiple subapertures to produce a large area topography. The first step is detecting edge features and then projecting them on the OXY plane. The next step is correction of lateral coordinates by registering the edge curves in overlapping regions. The change of lateral coordinates is linearly related to the lateral shifts and clocking angle which are estimated by simply solving a linear least-squares problem. In the final step, height change is also linearly related to the piston and tip-tilt of subapertures. Hence it is corrected by minimizing the height difference in overlapping regions, which is again modeled as a linear least-squares problem. The stitching method is experimentally verified on a holographic sample. Totally seven by seven subapertures are measured with an interference microscope and seamlessly stitched together. [ABSTRACT FROM AUTHOR]

The computer-generated holograms (CGH) are the core component to solve the problem of complex surface measurement. Pattern distortion is an important error source that affects its testing accuracy. This paper presents an evaluation method for the influence of pattern distortion on wavefront error. Firstly, the technical means of characterizing pattern information of CGH by optical element detection system was expounded. Then, the simulation model of wavefront error distribution was established to study the effect of pattern distortion on CGH testing accuracy. Finally, we verified the feasibility of the evaluation method based on the experimental research. [ABSTRACT FROM AUTHOR]

Abstract: We present a method for calibrating the position error of phase retrieval with transverse translation diversity in optical wavefront in situation where the position error sharply influences algorithm precision. This method involves testifying that the essence of the position error in phase retrieval is the translation in frequency domain and the minimum of iterative error against position error reaches when there is no position error. Then the least square method is used for fitting the relationship between the iterative error and the assumed position error in polynomial function. The computer simulations used to prove the validity of this method are described. The results indicated that this method can calibrate the position error to approximately 1/500mm which nearly has no influence on the phase retrieval. [Copyright &y& Elsevier]

[Display omitted] • The method of improving dispersion of indium polyphthalocyanine (InPPc) has been proposed. • The sodium dodecylbenzenesulfonate (SDBS) modification induces the matched surface hydrophilicity of carbon nanotubes (CNT) with InPPc. • The InPPc/SDBS@CNT exhibits the increased exposure of active site and electron-deficient In center. Molecular catalysts have emerged as the promising candidate for oxygen reduction to hydrogen peroxide (H 2 O 2). Dispersing homogeneously molecular catalyst on carbon support is the prerequisite for actual electrocatalysis application. Herein, we proposed a novel strategy of modification with sodium dodecylbenzenesulfonate (SDBS) to improve dispersion of indium polyphthalocyanine (InPPc) on carbon nanotube (CNT). The SDBS modification induces the matched surface hydrophilicity of CNT with InPPc, preventing InPPc aggregation. As a result, the InPPc/SDBS@CNT exhibits a remarkable onset potential of 0.84 V vs. RHE and selectivity of > 95 %, superior to InPPc/CNT and most recently reported catalysts. In situ Raman spectrum identifies the critical *OOH intermediate during H 2 O 2 formation on InPPc/SDBS@CNT. Importantly, the InPPc/SDBS@CNT presents a prominent H 2 O 2 production rate of 24.88 mg/cm2/h over 12 h in flow cell. This work provides an effective strategy to promote practical application of molecular catalysts. [ABSTRACT FROM AUTHOR]

• Complete characterization of surface error and thickness variation for hemispherical shells. • Interpretation and correction of pixel misalignment and mapping distortion. • Full aperture error map available through subaperture stitching. • Polar harmonics decomposition related to resonator performance. Geometric errors including the surface error and thickness variation of a hemispherical shell are determinant of the system performance, e.g. the frequency splitting of a hemispherical resonator gyroscope. Therefore, complete characterization at 0.1 µm level of accuracy is required which is difficult with current roundness measuring instruments. This paper presents an interferometric method for axially eccentric hemispherical shells. The outer surface and inner surface are measured individually by simply translating the shell along its anchor axis. The two measurements are registered after correction of pixel misalignment and mapping distortion through ray tracing. Thickness variation is then calculated from their difference. A multi-axis platform is designed to scan multiple subapertures covering the hemispherical shell. All subapertures are stitched together with misalignment corrected, according to the minimized inconsistency in the overlapping region of neighboring subapertures. The full aperture map is thus obtained for both the surface error and thickness variation. Polar harmonic representation is suggested by applying annular Zernike polynomial fitting. The method is experimentally demonstrated and validated with roundness cross test. [ABSTRACT FROM AUTHOR]

• Mechanical behaviors of AuPt alloys are investigated from atomic level. • Monocrystalline AuPt alloy is susceptible to work hardening at low temperature. • Mechanical properties of AuPt alloy are improved greatly by twining boundary. • Mechanical behavior of nanocrystalline AuPt alloy depends on grain size strongly. AuPt alloys are widely applied in electronics, aerospace, and precision equipment fields. A thorough understanding of the mechanical behavior of AuPt alloys is critical for their potential applications. Here, we leverage molecular dynamics (MD) method to for the first reveal the effects of microstructure and temperature on mechanical behavior of AuPt alloys from atomic level. The nanoindentation of monocrystalline (MC), nanotwinned (NT), and nanocrystalline (NC) AuPt alloys are performed. The results demonstrate that the mechanical properties of the MC AuPt alloy are excellent at 77 K because of dislocation strengthening while poor at high temperature due to amorphous behavior. The introduction of twinning boundary (TB) greatly improves the mechanical properties of AuPt alloy by preventing the stress spread and promoting dislocation activity. The mechanical behavior of NC AuPt alloy is strongly dependent on grain size. With increasing average grain size, the dominant plastic deformation mechanism of NC AuPt alloy changes from GB migration to dislocation motion and then to GB destruction. An appropriate grain size should be selected to inhibit GB migration or GB destruction, thereby achieving the enhancement of NC AuPt alloy through dislocation strengthening. This work provides an important theoretical basis for the subsequent design of AuPt alloys with desirable mechanical performances to extend the application prospects of noble metals. [Display omitted] [ABSTRACT FROM AUTHOR]