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Rational water and fertiliser management have an important impact on alfalfa production. This research aimed to explore the effects of water and phosphorus (P) fertiliser on water‐use efficiency (WUE) and phosphorus‐recovery efficiency (PRE) of each cut of alfalfa under drip irrigation and to determine the optimal interaction ratio of water and phosphorus to improve the quality and yield of alfalfa. Different irrigation levels were set, i.e., 5250, 6000 and 6750 m3/ha (referred to as W1, W2, W3, respectively), and P fertiliser levels (0, 50, 100 and 150 kg/ha P2O5 referred to as P0, P1, P2, P3, respectively) were set to determine the hay yield and nutrient quality of each cut of alfalfa under drip irrigation. The hay yield of each cut of alfalfa increased first and then decreased with increased P fertiliser under the same irrigation amount. WUE decreased gradually with an increasing amount of irrigation under the same P application rate. The WUE of alfalfa increased first and then decreased with the increase of P application rate under the same irrigation amount, and WUE was 0.20%–4.75% (2016) and 1.31%–6.22% (2017) higher in the P treatments than in the non‐phosphorus treatments. PRE decreased gradually with increasing P application rate under the same irrigation amount. Therefore, we concluded that moderate irrigation (6000 m3/ha) and P fertiliser (100 kg/ha) optimised WUE, PRE, hay yield and nutrient quality. [ABSTRACT FROM AUTHOR]

An efficient and convenient method was developed for the preparation of 3-sulfenylindoles via a cellulose-derived Fe3O4@Pd NPs catalyzed heterogeneously C–H sulfenylation of indoles. This approach provides an effective synthetic route to an important class of indoles derivatives and features high efficiency, easy operation, good practicality, and environmental friendliness. The recoverable catalyst was separated from the reaction mixture using an outside magnetic field and can be recycled five times without huge loss of catalytic performance. An efficient method was developed for the preparation of 3-sulfenylindoles via cellulose-derived Fe3O4@Pd NPs catalyzed heterogeneously C–H sulfenylation of indoles. [ABSTRACT FROM AUTHOR]

In order to improve the osteoconductivity and the osteoinductivity of bone tissue engineering scaffold, a novel bi-phase strontium-doped magnesium phosphate/calcium silicate (Sr-MP/CSC) composite scaffold was fabricated by the self-solidifying/particulate leaching method. The bi-phase composition of the well-crystallized struvite grains wrapped by the calcium silicate floccules was propitious to the deformability and toughness of composite scaffold, and the porous structure with interconnected macropores of 100–400 µm was beneficial to supporting the tissue growth and transporting nutrients and metabolites. When the Sr-MP/CSC composite scaffolds were degraded in the simulated physiological environment, the doped strontium could be sustainably released together with Ca 2+ , Mg 2+ , PO 4 3- and silidous ions. The proliferation and osteogenic differentiation of rat bone marrow stromal cells (BMSCs) on these composite scaffolds were obviously promoted. More valuably, the Sr-doped MP/CSC scaffolds exhibited the more obvious promotion to ALP activity, Col I and OCN expression than the un-doped MP/CSC scaffold, especially in the later stage. The results suggested that the strontium combined with calcium, magnesium and silicon could synergically promote osteogenesis, and the Sr-MP/CSC composite might be one of the promising bone tissue engineering scaffold materials. [ABSTRACT FROM AUTHOR]

The corrosion mechanisms and kinetics of AA1085 in Li 2 SO 4 and LiNO 3 aqueous rechargeable lithium-ion battery electrolytes were investigated at pH 11 using chronoamperometry. The corrosion kinetics of AA1085 is controlled by the electrolyte concentration level and the anodic potentials. AA1085 is susceptible to crystallographic pitting corrosion in Li 2 SO 4 electrolytes. The rates of pit nucleation and pit growth both decreased at higher Li 2 SO 4 concentrations or at lower anodic potentials. AA1085 passivates against pitting corrosion in LiNO 3 electrolytes due to the formation of a thick, uniform corrosion product layer. The growth rate of the passive film was slightly enhanced by increasing the electrolyte concentration and anodic potentials. X-ray photoelectron spectroscopy spectra showed the formation of a thin sulfate-incorporated passive film on the electrode, which comprises Al 2 (SO) 4 18H 2 O, Al(OH)SO 4 and Al(OH) 3 , before the occurrence of pitting growth in 2 M Li 2 SO 4 electrolyte. The thick corrosion product layer formed in 5 M LiNO 3 electrolyte was composed of Al(OH) 3 and AlOOH. Raman spectroscopy on deionized water, LiOH solution, Li 2 SO 4 and LiNO 3 electrolytes depicted changes of solution structure with increasing electrolyte concentration. The influence of extrinsic and intrinsic factors on the corrosion kinetics of AA1085 in Li 2 SO 4 and LiNO 3 electrolytes at pH 11 are discussed in detail. [ABSTRACT FROM AUTHOR]

In the traditional machining method, the surface quality will get worse during the surface figuring process while the surface figure will be destroyed after ultra-smooth polishing process. To obtain an ultra-precision optical surface, these two processes are conducted iteratively which is time-consuming and unstable. A new fabrication method combined with the magnetorheological finishing (MRF) and hydrodynamic effect polishing (HEP) technology was presented. The surface figure error can be quickly depressed by MRF due to its high deterministic figuring ability, while the surface quality will get worse due to the introduction of MRF polishing marks. The material removal of HEP depends on the chemical interaction between the nanoparticles and workpiece in elastic mode, and an ultrasmooth surface with sub-nanometer level can been easily achieved with the surface figure well maintained. The experiment results show that the MRF polishing marks are removed clearly and the surface figure is well maintained after HEP process. Combined with MRF, a quartz glass with initial figure accuracy of 0.415 λ RMS (λ = 632.8 nm), mid-spatial frequency and high spatial frequency roughness of 0.407 nm RMS and 0.525 nm RMS has been improved to figure accuracy of 0.05 λ RMS, mid-spatial frequency and high spatial frequency roughness of 0.268 nm RMS and 0.163 nm RMS. Power spectral density (PSD) analysis indicated that the surface spatial frequency error has all been greatly depressed. It demonstrates HEP is an effective ultra-smooth polishing method with good ability to maintain the initial surface figure. [ABSTRACT FROM AUTHOR]

In the field of smart manufacturing, the data-driven scheduling approach has become an effective way to solve the smart shop floor scheduling problem with high complexity and dynamics. However, most existing approaches rely too heavily on manual supervision in implementation, resulting in poor adaptability and effectiveness in dynamic production environments. Therefore, this paper proposes a self-adaptive scheduling approach based on double deep Q-network (DDQN), which can reduce manual supervision and realize the autonomy of the whole scheduling process. In the presented approach, first, a self-adaptive scheduling framework, which forms a closed-loop optimization structure for scheduling model evaluation, generation/updating, and application, is designed. Second, the interactive learning mechanism of reinforcement learning is introduced, and the scheduling model is generated through the DDQN algorithm without manual supervision. In addition, dynamic reward function based on simulation is proposed to promote the rationality and accuracy of the reward in reinforcement learning. The effectiveness of the proposed approach is validated on a semiconductor production shop floor, and the experimental results illustrate that the proposed approach can improve the effectiveness of self-adaptive scheduling and significantly reduce the time and labour costs in the dynamic production environments. [ABSTRACT FROM AUTHOR]

Aqueous rechargeable lithium-ion batteries (ARLBs) use aqueous electrolytes, which create conditions where corrosion may occur when aluminum is used as the current collector. The electrochemical stability of AA1085 in 2 M LiSO and 5 M LiNO aqueous electrolytes was evaluated over a range of pH conditions by cyclic voltammetry, linear sweep voltammetry, and chronoamperometry. Aluminum presented high corrosion resistance at pHs 5, 7, and 9 within the stability windows of both electrolytes. At the pH 11 condition, 2 M LiSO is capable of inhibiting aluminum from pitting but the inhibiting effect is not sustainable and crystallographic pitting occurs under a continuously applied anodic potential. Aluminum was well passivated against pitting in 5 M LiNO electrolyte at pH 11 due to the formation of a thick corrosion product barrier layer. Raman spectra depicted the presence of sulfate and nitrate anions on aluminum surface after cyclic voltammetry at pH 11. Inductively coupled plasma results showed that the amount of dissolved aluminum in electrolyte after cyclic voltammetry increases when pH increases from 5 to 11. The chemical adsorption mechanisms of sulfate and nitrate anions on aluminum were proposed to explain the dependency of electrochemical stability of aluminum on pH, anodic potential, and type of anions. The applicability of aluminum as current collector in ARLB using the 2 M LiSO and 5 M LiNO electrolytes is discussed. Graphical abstract: [ABSTRACT FROM AUTHOR]

Ti-Cu sintered alloys, Ti-Cu(S) alloy, have exhibited good anticorrosion resistance and strong antibacterial properties, but low ductility in previous study. In this paper, Ti-Cu(S) alloys were subjected to extrusion processing in order to improve the comprehensive property. The phase constitute, microstructure, mechanical property, biocorrosion property and antibacterial activity of the extruded alloys, Ti-Cu(E), were investigated in comparison with Ti-Cu(S) by X-ray diffraction (XRD), optical microscopy (OM), scanning electronic microscopy (SEM) with energy disperse spectroscopy (EDS), mechanical testing, electrochemical testing and plate-count method in order to reveal the effect of the extrusion process. XRD, OM and SEM results showed that the extrusion process did not change the phase constitute but refined the grain size and Ti 2 Cu particle significantly. Ti-Cu(E) alloys exhibited higher hardness and compressive yield strength than Ti-Cu(S) alloys due to the fine grain and Ti 2 Cu particles. With the consideration of the total compressive strain, it was suggested that the extrusion process could improve the ductility of Ti-Cu alloy(S) alloys. Electrochemical results have indicated that the extrusion process improved the corrosion resistance of Ti-Cu(S) alloys. Plate-count method displayed that both Ti-Cu(S) and Ti-Cu(E) exhibited strong antibacterial activity (> 99%) against S. aureus. All these results demonstrated that hot forming processing, such as the extrusion in this study, refined the microstructure and densified the alloy, in turn improved the ductility and strength as well as anticorrosion properties without reduction in antibacterial properties. [ABSTRACT FROM AUTHOR]

We present a new reconstruction method for measuring profile of large, ultraprecise absolute optical surfaces with a compact interferometer. The profile of workpiece can be reconstructed exactly with high lateral resolution and large non-equidistant scanning step. Both systematic errors of the interferometer and height offsets of the scanning stage can be eliminated. Additional angular measurement can be used to measure pitching angles of the scanning stage. The exact reconstruction method is verified by computer simulation and on-machine measurement experiment. [ABSTRACT FROM AUTHOR]

Abstract: We present a method for optical wavefront measurement using phase retrieval with subaperture stitching method in situations where detected intensity patterns are undersampled or where the limit of aberrations is determined by the largest spot size overfilling the detector array. In this technique we use a smaller moving subaperture to produce a number of adequately sampled intensity patterns captured by the detector located near the focus plane. These patterns are then used to retrieve the full-aperture wavefront through an optimization phase retrieval algorithm. The relationship between the optimization parameters of moving subaperture and the support information is given. Then expressions for the gradient of an error metric with respect to the optimization parameters are presented. An experimental setup used to measure the reflected wavefront of a concave mirror by employing this method is arranged. The experimental results indicate that the phase retrieval results are in excellent agreement with that obtained with interferometer, which confirms the validity of this method. [Copyright &y& Elsevier]

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]

Abstract: Phase retrieval technology for off-axis ellipsoid surface measurement with a high dynamic range algorithm is proposed in this paper. A high dynamic range algorithm (HDRA) for phase retrieval is proposed. We proved the validity of it in simulation. Then the HDRA is used to measure an off-axis ellipsoid. The measurement setup was established and the HDRA was applied to retrieve the surface shape of the off-axis ellipsoid. The experimental results show that the phase retrieval results are good agreement with that obtained by interferometer, which confirms the validity of this method. [Copyright &y& Elsevier]

Abstract: Subsurface damage generated in manufacturing processes directly influences performances of optical elements, however, the rapid inspection of subsurface damage is unresolved for it is covered under surface. For the purpose of rapid, accurate, and non-destructive measurement of subsurface damage produced in optical grinding and lapping processes, a theoretical model of relationship between subsurface damage and surface roughness was established through investigating median and lateral crack system in brittle surface induced by sharp indenter, and contribution of elastic stress field to the median crack propagation was also considered in the loading cycle. With this model, subsurface damage depth can be predicted accurately via measuring surface roughness of manufactured optical elements. The subsurface damage depth and surface roughness of ground and lapped BK7 glass were measured by MRF (magnetorheological finishing) spot technique and contacting profilometer, respectively, in order to verify the validity of the relationship model. The results show that the relationship model is convenient and accurate in predicting the subsurface damage depth. And there exists monotone increasing non-linear correlation between subsurface damage depth and surface roughness ( value) in optical grinding and lapping processes. At last the relationship between subsurface damage depth and process conditions in grinding and lapping processes and material mechanical properties is discussed. [Copyright &y& Elsevier]

Background: Whether perceived stress is associated with loneliness and depressive symptoms in general adults, and to what extent sleep quality mediates the associations, remains unknown. The aim of this study was to estimate the associations of perceived stress with loneliness and depressive symptoms, and the mediating role of sleep quality in these associations. Methods: Cross-sectional data on 734 participants (aged 18–87 years) were analyzed. Perceived stress was assessed using the 10-item Perceived Stress Scale (PSS-10; range 0–40). Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI; range 0–21). Loneliness was assessed using the three-item short form of the Revised University of California, Los Angeles (UCLA) loneliness scale (range 3–9). Depressive symptoms were assessed using the 10-item Center for Epidemiologic Studies Depression (CESD-10) Scale (range 0–30). General linear regression models, multivariable logistic regression models, and formal mediation analysis were performed. Results: After adjustment for age and sex, we found that with each 1-point increment in the perceived stress score, both the loneliness score (β = 0.07; 95% confidence interval [CI]: 0.06, 0.08) and depression score (β = 0.45; 95% CI: 0.40, 0.49) increased significantly. Robust results were observed when adjusting for more confounders. Furthermore, sleep quality mediated 5.3% (95% CI: 1.3%, 10.0%; P = 0.014) and 9.7% (95% CI: 6.2%, 14.0%; P < 0.001) of the associations of perceived stress score with loneliness score and depression score, respectively. Conclusions: In general Chinese adults, perceived stress was positively associated with loneliness and depressive symptoms, and sleep quality partially mediated these associations. The findings reveal a potential pathway from perceived stress to mental health through sleep behaviors, and highlight the importance of implementing sleep intervention programs for promoting mental health among those who feel highly stressed. [ABSTRACT FROM AUTHOR]

A novel magnetorheological finishing (MRF) method, which is named Lap-MRF, is proposed in this paper. The magnetorheological fluid (MR fluid) in the polishing zones can be renewed continuously so that the determinacy is ensured. A lap, instead of a large polishing wheel, is used to expand the polishing area, which improves the material removal rate largely. Lap-MRF uses flexible MR fluid as polishing pad to match the surface well. Moreover, the polishing pad executes planetary motion so as to obtain smooth surface. In this paper, the principle of Lap-MRF and the theoretical model of material removal rate are presented. Using the finite element analysis method, the permanent magnet unit is simulated and a multi-parameter optimization is conducted to improve the performance of Lap-MRF. Finally, a series of polishing experiments and simulation process are carried out. For K9 sample, the volume removal rate is up to 0.76 mm3/min and its relative change rate is less than 5.5%. For silicon modification layer sample, the surface roughness is improved to 0.788 nm RMS (root mean square) from 1.610 nm RMS. There is no deep pit and the polishing ripple is not apparent on the surface. For Φ1000 mm flat mirror, the convergence efficiency of simulation process is up to 97.2%. These results verify the validity of the proposed method, which makes Lap-MRF to be a promising finishing technology for large aperture mirrors. [ABSTRACT FROM AUTHOR]

The fabrication of high-quality freeform surfaces is based on ultra-precision diamond turning with fast tool servo (FTS) technology which allows direct machining of the freeform surfaces with sub-micrometric form accuracy and nanometric surface roughness. Surface roughness is an important factor in evaluating the performance of the optical freeform surfaces. This paper presents a theoretical and experimental analysis of surface generation in ultra-precision single-point diamond turning. In this model, we take into consideration the basic machining parameters as well as the relative vibration between the workpiece and the tool in both the cutting and feeding directions. Theoretical model is built to predicting the surface roughness of machined flat surface as well as freeform surfaces. A series of experiments have conducted and the results show good correlation between the theoretical model and the fabricated surfaces. [ABSTRACT FROM AUTHOR]

Single point diamond turning (SPDT) based on tool servo system is one of the significant techniques to fabricating the optical freeform surfaces. The conventional fast tool servo (FTS) actuated by piezoelectric actuator has the problem of short stroke, while the drawback of the slow tool servo (STS) is low frequency response. This paper briefly presents a novel long range fast tool servo (LRFTS) with high frequency response and long stroke. The total stroke can reach up to 30 mm. The LRFTS uses a voice coil motor as the actuating element and air bearings as the guide mechanism. The LRFTS utilizes a linear encoder to measure the displacement of the tool for closed loop control. The servo performance of the LRFTS system's amplitude and frequency response is analyzed. The physical model of the LRFTS is identified. A series of experiments have been conducted to verify the performance of the designed LRFTS. Micro-lens array fabrication experiments on an aluminum part are conducted using the designed LRFTS. The factors influencing the surface roughness have been analyzed. [ABSTRACT FROM AUTHOR]

Optical freeform surfaces have been applied in optoelectronic systems more and more widely, but it is difficult to fabricate this kind of freeform surface optics with high quality and high efficiency. Ultra-precision diamond turning machining technology based on a fast tool servo system is an effective and precise process for fabricating optical freeform surfaces. This paper develops a novel fast tool servo system, which has a total stroke of 30 mm and a maximum acceleration of 920 m/s. In this paper, we develop a theoretical and experimental investigation on the 3D surface generation of a rear-view mirror which is a typical optical freeform surface in single-point diamond tuning using a fast tool servo system. The experimental results are tested and analyzed, which indicate that the performances are satisfied. The field of view obtained by the designed rear-view mirror is much larger than the flat mirror, while the distortion is minimal. [ABSTRACT FROM AUTHOR]

Bimodal mesoporous titanosilicate beads with interconnected three-dimensional pore architecture (BMB-TiSil) were synthesized through a one-pot dual-templating method in the presence of a porous anion-exchange resin. Whereas the framework mesopores centered at 3.5 nm are generated by the templating effect of the surfactant, the continuous large mesopore system originates from removal of the resin body. In the green epoxidations of alkene with aqueous H 2 O 2 , BMB-TiSil showed higher turnover frequency (TOF) based on the alkene conversion and higher epoxide yield than Ti-MCM-41, which is mainly ascribed to the continuous large mesopore system favoring the diffusion of the reactants and products to and from the active titanium sites. Importantly, BMB-TiSil is a stable catalyst immune to titanium leaching, and can be reused in three successive catalytic cycles without significant loss of activity due to its continuous large mesopore system and stable Ti-sites. [ABSTRACT FROM AUTHOR]

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]

Aspheric optics has been widely used in the space telescope system. The large amount of material removal and mid-frequency errors district the high-precision and high-efficiency fabrication of large-scale aspheric optics. On the basis of parsing the figuring ability of tool influence functions (TIFs) and principles of smoothing polishing technology, the multi-TIFs process is proposed in this paper. Then the selection principle and replacement time of TIFs have been discussed. Furthermore, the multi-TIFs process is optimized with frequency filtering method. This filtering method with multi-TIFs can obtain better surface accuracy in a faster way compared to the traditional method. Finally, a Φ540mm SiC off-axis aspheric mirror is polished to verify the proposed method. [ABSTRACT FROM AUTHOR]

We report for the first time the discovery of reversible n–p conduction type switching in a chalcogenide, NaCu5S3, without structural transition. AC impedance and first-principles simulations of the ionic migration confirmed the local melting trends of the hexagonal copper lattice at high temperatures, which could result in superionic conductivity within NaCu5S3. [ABSTRACT FROM AUTHOR]

Alfalfa (Medicago sativa L.) is an important forage legume in arid areas, but limited water resources and low fertilizer utilization have restricted its agricultural development. Meanwhile, studies on the effects of integrated water and phosphorus on production performance and water‐use efficiency and phosphorus‐use efficiency of alfalfa, especially on hay yield, phosphorus accumulation, and total phosphorus uptake are rarely reported under drip irrigation. The treatments were a factorial combination of three irrigation rates (5,250, 6,000, and 6,750 m3/ha per year) and four P rates (0, 50, 100, and 150 kg/ha per year) and consisted of 12 treatments for water and P management, arranged in a randomized complete block design with three replicates. Total hay yield and water‐use efficiency and phosphorus‐use efficiency of alfalfa in P2 treatment were significantly greater than those in the P1 and P3 treatments (p <.05), and the total hay yield of alfalfa with phosphorus application increased by 7.43%–29.87% compared with that in the nonphosphorus (P0) treatment under the same irrigation amount. The total phosphorus and available phosphorus concentrations in the 0–20 cm soil layer were greater than those in the 20–40 cm and 40–60 cm soil layers compared with those in the P0 treatment. Correlation analyses showed that total hay yield was significantly positively correlated with total phosphorus uptake and water‐use efficiency (p <.01). The accumulated phosphorus concentration was significantly positively correlated with total phosphorus and available phosphorus concentration (p <.01) and was positively correlated with the phosphorus‐use efficiency (p <.05). The membership function method was used to evaluate all the indicators, and the three treatments that had the greatest influence on the production performance of alfalfa were, in order, W2P2 > W3P2 > W1P2. Therefore, an irrigation rate of 6,000 m3/ha and a phosphorus application rate of 100 kg/ha per year should be considered as the best management for both high yield and water‐use efficiency and phosphorus‐use efficiency of alfalfa. [ABSTRACT FROM AUTHOR]

The p38MAPKs (mitogen-activated protein kinases) signaling contributes a pivotal role in mammalian ovarian follicular development; however, the knowledge regarding their expression in geese remains unresolved. The objective of the current study was to determine the spatio-temporal expression of heat shock protein 27 (HSP27) and mitogen- and stress-activated protein kinase 1 (MSK1) genes in the prehierarchical follicles during geese ovarian development. The prehierarchical follicles samples were harvested from 35- to 37-week-old healthy laying geese. HSP27 and MSK1 relative expression in various sized prehierachical follicles was detected by real-time quantitative polymerase chain reaction (RT-qPCR) and western blotting. Follicular wall localization of HSP27 and MSK1 was examined by using immunohistochemistry. Our results at mRNA level indicated that HSP27 was highly expressed in middle white follicles whereas MSK1 was predominantly expressed in small white follicles. The western blotting results for HSP27 and MSK1 were inconsistent with the RT-qPCR results in various stages of prehierachical follicular development but noticeably, HSP27 proteins were still expressed more in middle white follicles while MSK1 proteins were more abundant in primary follicles. At different stages of prehierarchical development, immunodetections in the granulosa and theca cells revealed that HSP27 was intensively localized in middle white follicles while strong detections of MSK1 were observed in large white follicles. These results indicate HSP27 and MSK1 might be associated to the key regulators of folliculogenesis in geese. [ABSTRACT FROM AUTHOR]

MXenes are great catalysts for MgH 2 hydrogen storage material. Nevertheless, the synthesis of MXenes needs a large quantity of corrosive HF solution to remove the Al layers from the MAX materials, which is harmful to the environment. In this work, TiNbAlC MAX was employed without HF-treatment to tailor the hydrogen storage of MgH 2. The MgH 2 + 10 wt% TiNbAlC composite was prepared by ball milling. The addition of 10 wt% TiNbAlC greatly reduces the onset temperature of MgH 2 desorption from 332 °C to 197 °C. The composite can desorb 6.2 wt% of H 2 in 10 min at a constant temperature of 300 °C. Moreover, the dehydrided MgH 2 + 10 wt% TiNbAlC composite can start to absorb hydrogen at room temperature under a H 2 pressure of 6 MPa. The hydrogen desorption activation energy of the composite was calculated by Kissinger's method to be 101 kJ mol−1. Microstructures studies demonstrated that TiNbAlC will partially react with MgH 2 /H 2 to form TiH 1.971 , which can act as a "hydrogen pump" to facilitate the hydrogen sorption of MgH 2. This work suggests that MAX materials are good catalysts for hydrogen storage of MgH 2 and provides new insight into the role of MAX phase in tailoring the hydrogen storage of Mg-based hydrogen storage materials. [Display omitted] • TiNbAlC can significantly enhance the hydrogen storage of MgH 2. • Enhancing effect of TiNbAlC is comparable to many MXenes • TiNbAlC partially transform to active TiH 1.971. • TiH 1.971 acts as a "hydrogen pump" for hydrogen sorption of MgH 2. [ABSTRACT FROM AUTHOR]

Hydrodynamic effect polishing (HEP), in which the material is removed in elastic region by chemical impact reaction, can effectively remove the surface/subsurface damage to get an ultrasmooth surface. However subsurface damage contains scratches and machining residual stress are hidden below the surface and can’t be easily detected. The subsurface/surface properties such as hardness and elastic modulus have direct relationship with the subsurface damage. Therefore, a nano-imprint method analysis of the optical subsurface quality was presented to evaluate the hydrodynamic effect polishing process effect. Polishing experiment was conducted on a conventional pad pre-polished silica glass. The surface before and after polishing process was firstly observed by atomic force microscope and ZYGO white-light interferometer. The observation shows the surface damage such as the scratches and bump structures are completely removed by HEP process, and the surface roughness rms value decreased to near 0.3 nm. To evaluate the subsurface damage, nano-imprint was conducted on the processed and unprocessed area under different load with different impressed depth. The imprint results show the processed surface become soft and easily be impressed, while the unprocessed surface becomes hard. The processed and unprocessed surface shows the same impress depth when impressed depth exceeded 200 nm. Analysis shows the surface becomes hard under the effect of the residual stress in subsurface damage which is generated in the traditional machining process with material removal in brittle or plastic mode. Material is removed in elastic mode by chemical impact reaction in HEP, and the surface/subsurface damage can be effectively removed. It demonstrates that HEP processed surface properties are much close to the bulk material. [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]

Atmosphere plasma etching methods have been applied to the machining of optics. However, due to the high chemical stability and inertness of silicon carbide (SiC) ceramics, it seems difficult to improve the material removal rate (MRR) for conventional etching methods. We have found MRR will be significantly improved while arc forms between the inductively coupled plasma and SiC ceramic surface. This etching method is called arc-enhanced plasma machining (AEPM) technology. Arc-enhanced plasma (AEP) is represented as the secondary of a high-frequency transformer considering capacitive coupling in this paper. Radio frequency (RF) voltage in AEP is measured. The RF voltage of plasma is extremely high to form arc when plasma is close to the SiC ceramic surface. The measurement results of RF voltage at the metal-plasma interface show that the arc formation is related to the distance between source jet and workpiece ( D ). When D is small, a nonconductive layer of cooled argon forms over the workpiece surface, preventing arcing. Trenches are etched on SiC ceramic surface with different D , finding that the MRR is improved under the arcing action and the optimal D is obtained. [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]

One-dimensional ion-beam figuring (1D-IBF) can improve grazing-incidence reflective optics, such as Kirkpatrick-Baez mirrors. 1D-IBF requires only one motion degree of freedom, which reduces equipment complexity, resulting in compact and low-cost IBF instrumentation. Furthermore, 1D-IBF is easy to integrate into a single vacuum system with other fabrication processes, such as a thin-film deposition. The NSLS-II Optical Metrology and Fabrication Group has recently integrated the 1D-IBF function into an existing thin-film deposition system by adding an RF ion source to the system. Using a rectangular grid, a 1D removal function needed to perform 1D-IBF has been produced. In this paper, demonstration experiments of the 1D-IBF process are presented on one spherical and two plane samples. The final residual errors on both plane samples are less than 1 nm r.m.s. The surface error on the spherical sample has been successfully reduced by a factor of 12. The results show that the 1D-IBF method is an effective method to process high-precision 1D synchrotron optics. [ABSTRACT FROM AUTHOR]

The Wingless-types/beta-catenin (Wnt/β-catenin) signaling pathway plays an important role in embryonic development and affects the physiological development processes of feather follicles. To investigate the role of Wnt/β-catenin pathway in regulating feather follicles morphogenesis, in ovo injection of CHIR-99021, an activator of the Wnt/β-catenin signaling pathway, was conducted in chick embryo model. Initially, a total of 40 embryos were used to assess feather follicles morphogenesis and the expression of β-catenin (E9–E17). The histological results showed that feather follicle morphogenesis was mainly completed from E9 to E17. β-catenin was involved in the processing of the appearance of dermal cell condensation (E9) and the completion of the feather follicles morphogenesis (E17). Next, a total of 160 fertilized eggs were randomly divided into 8 groups for in ovo injection at E9, including a Normal Saline injected group (CON) and the 500, 1,000, 2,000, 5,000, 10,000, 50,000, and 100,000 ng CHIR-99021 groups. Dorsal skin tissue samples were collected at E17 for investigating feather follicles morphology and expressions of β-catenin and lymphoid enhancerbinding factor-1 (LEF1) at gene and protein levels. The results showed that feather follicle diameter in the injected groups were significantly (P < 0.05) increased with limit dose-independence compared to the CON group. CHIR-99021 significantly (P < 0.05) influenced the mRNA expressions of catenin beta-1 ( CTNNB1 ) and downstream target LEF1. In ovo injection of CHIR-99021 caused that β-catenin and LEF1 were significantly (P < 0.05) increased followed the increased doses as determined by western blotting. The immunochemical results showed that β-catenin was detected in the dermal papilla of feather follicles. Given these results, this study suggests to developmental biology that in ovo injection of CHIR-99021 promoted feather follicles morphogenesis and development via activating Wnt/β-catenin signaling pathway and upregulating downstream target LEF1 during embryonic period in chick embryo model. Moreover, CHIR-99021 may be a strong candidate to promote the animal feather/hair industry, especially as a reference for bird feather production. [ABSTRACT FROM AUTHOR]

It is necessary to quantitatively compare two measurement results which are typically in the form of error maps of the same surface figure for the purpose of cross test. The error maps are obtained by different methods or even different instruments. Misalignment exists between them including the tip-tilt, lateral shift, clocking and scaling. A fast registration algorithm is proposed to correct the misalignment before we can calculate the pixel-to-pixel difference of the two maps. It is formulated as simply a linear least-squares problem. Sensitivity of registration error to the misalignment is simulated with low-frequency features and mid-frequency features in the surface error maps represented by Zernike polynomials and spatially correlated functions, respectively. Finally by applying it to two cases of real datasets, the algorithm is validated to be comparable in accuracy to general non-linear optimization method based on sequential quadratic programming while the computation time is superiorly incomparable. [ABSTRACT FROM AUTHOR]

Surface slope profile is widely used in the metrology of grazing-incidence reflective optics instead of surface height profile. Nevertheless, the theoretical and experimental model currently used in deterministic optical figuring processes is based on surface height, not on surface slope. This means that the raw slope profile data from metrology need to be converted to height profile to perform the current height-based figuring processes. The inevitable measurement noise in the raw slope data will introduce significant cumulative error in the resultant height profiles. As a consequence, this conversion will degrade the determinism of the figuring processes, and will have an impact on the ultimate surface figuring results. To overcome this problem, an innovative figuring model is proposed, which directly uses the raw slope profile data instead of the usual height data as input for the deterministic process. In this paper, first the influence of the measurement noise on the resultant height profile is analyzed, and then a new model is presented; finally a demonstration experiment is carried out using a one-dimensional ion beam figuring process to demonstrate the validity of our approach. [ABSTRACT FROM AUTHOR]

Abstract: Conical hydrostatic bearings with two different compensating devices have been proposed in this paper, which are classified as variable slot compensated hydrostatic bearing (VSHB) and fixed slot compensated hydrostatic bearing (FSHB), respectively. The mathematical models for them have been built with perturbation theory and solved by finite element method (FEM). Static loading experiment has been carried out to validate the research methodology. Then the static and dynamic characteristics of the proposed bearings have been comparatively studied. Results show that the VSHB exhibits a better radial performance of load carrying capacity and stiffness, but a worse radial damping performance, compared with FSHB under the same geometric and operational conditions. [Copyright &y& Elsevier]

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: The tensile properties and fracture behaviour of A350LF2 steels after exposure to wet H2S environments were investigated by corrosion and tensile testing. The results suggest that relative tensile strength and plasticity loss increased as hydrogen concentration increased. Greater tensile property damage occurred in steel that contained more large-size inclusions. When hydrogen was released, the degree of relative strength and plasticity loss decreased. Fractography of the corroded samples exhibited mixed ductile–brittle rupture. Fractured areas with quasi-cleavage features increased with increasing hydrogen concentration. Flakes appeared in the steel with a low sulphur content and low hydrogen concentration. [Copyright &y& Elsevier]

Abstract: Rocking mass resonator is widely used to design various sensors and actuators, which is a dual-axial symmetry resonator with high sensitivity. Q support is the dominant energy loss mechanism influencing its high sensitivity. The anchor types and support loads applied to attachment points of rocking mass resonator are analyzed. Then support loss is simplified as a model with a beam attached to a finite thickness plate at its end. The general formulations for power radiated into support structure are given. An accurate analytical model of support loss for rocking mass resonator has been developed and verified by experiments. When the thickness of resonator is 240μm, the measured Q can achieve a value of 589.1; while the thickness of resonator is reduced to 60μm, the measured Q can achieve a value more than 8500. The derived model is general and might be applicable to various micro beam resonators and anchor types, providing significant insight to design of high-Q rocking mass devices. [Copyright &y& Elsevier]

Abstract: In an ion-beam figuring (IBF) process, the desired material removal, which is specified to the contour algorithm to calculate dwell time, decides the calculated process time and the resulted residual surface figure error. Usually, an IBF process with more removal consumes a longer process time, although the resulted residual error is smaller, whereas an IBF process with less removal needs only a shorter process time, but the resulted residual error is greater. Therefore, in order to balance the process time and the residual error, an optimum removal should be determined. In this study, the characteristic relationship between the process time and the residual error on different specified removals is investigated first. The investigation shows that for smaller removals, the residual error decreases rapidly while the process time increases slowly, and for larger removals, the process time increases rapidly without much decrease in residual error. This characteristic makes the figure-prediction curve (process times vs. rediual errors (RMS)) often in the shape of the letter “L”. Therefore, the optimum removal can be determined at the corner of the curve. Finaly, experiments are performed to verify the proposed method. [Copyright &y& Elsevier]

Abstract: To meet the requirements of triaxial measurement of high-shock with a high accuracy, monolithic high-performance triaxial piezoresistive accelerometers are developed for 50,000–100,000× g measure range. An axial-stressed tiny-beam scheme is developed for the X and Y axial elements that features both high sensitivity and high resonant frequency, while a three-beam twin-mass structure is developed for Z-axis element that also features aforementioned high performance. The three sensing elements are monolithically integrated by micromachining techniques of double-sided deep etching combined with piezoresistive processes. The sensor chip of the triaxial accelerometer is 4.4mm×2.3mm×1mm in dimensions. A dropping-bar system is used to characterize the accelerometer. The sensitivity in X-, Y- and Z-axes are measured as 2.17, 2.25 and 2.64μV/g/5V, respectively, while the corresponding resonant frequency is 308, 303 and 164kHz. With the dropping bar shocking system, a time-domain separation method is developed, for the first time, to realize precise test of the cross-axis sensitivity. With the novel measurement technique, satisfactory cross-axis sensitivity (not higher than 2.1%) is experimentally obtained for all the three axial elements, which contributes to the high performance of the monolithic triaxial shock accelerometers. [Copyright &y& Elsevier]

Alfalfa (Medicago sativa L.) is an important forage legume in farming and animal husbandry systems. This study assessed the effects of arbuscular mycorrhizal fungi (AMF) and phosphate-solubilizing bacteria (PSB) on alfalfa growth under different phosphorus application levels. In this experiment, a complete randomized block design was used. The following four bacterial applications were used: inoculation of Funneliformis mosseae (Fm), inoculation of Bacillus megaterium (Bm), inoculation of mixed species (Fm × Bm) and noninoculation treatment (CK). Phosphorus (P) treatment was applied at the following four levels: 0 mg kg−1 (P0), 50 mg kg−1 (P1), 100 mg kg−1 (P2) and 150 mg P kg−1 (P3). The results showed that with the increase in phosphorus application, each index increased first and then decreased. The J2 treatment was significantly greater than the J0 treatment (P < 0.05) under the same bacterial treatment. In each cropping period the difference in each index to alfalfa was extremely significant under J, P treatment and J × P interactive treatment (P < 0.01). The indexes were compared by membership function. The priority order was as follows: J3P2 > J1P2 > J3P1 treatment. Therefore, when phosphorus was applied at 100 mg kg−1, the mixed inoculation of Fm × Bm was optimal, benefitting mycorrhiza growth and the production performance of alfalfa. [ABSTRACT FROM AUTHOR]

Geese feather production and the quality of downy feathers are additional economically important traits in the geese industry. However, little information is available about the molecular mechanisms fundamental to feather formation and the quality of feathers in geese. This study conducted de novo transcriptome sequencing analysis of two related geese species using the Illumina 4000 platform to determine the genes involved in embryonic skin feather follicle development. A total of 165,564,278 for Anser anser and 144,595,262 for Anser cygnoides clean reads were generated, which were further assembled into 77,134 unigenes with an average length of 906 base pairs in Anser anser and 66,041 unigenes with an average length of 922 base pairs in Anser cygnoides. To recognize the potential regulatory roles of differentially expressed genes (DEGs) during geese embryonic skin feather follicle development, the obtained unigenes were annotated to Gene Ontology (GO), Eukaryotic Orthologous Groups (KOG), and Kyoto Encyclopedia of Genes and Genomes (KEGG) for functional analysis. In both species, GO and KOG had shown similar distribution patterns during functional annotation except for KEGG, which showed significant variation in signaling enrichment. Anser asnser was significantly enriched in the calcium signaling pathway, whereas Anser cygnoides was significantly enriched with glycerolipid metabolism. Further analysis indicated that 14,227 gene families were conserved between the species, among which a total of 20,715 specific gene families were identified. Comparative RNA-Seq data analysis may reveal inclusive knowledge to assist in the identification of genetic regulators at a molecular level to improve feather quality production in geese and other poultry species. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the changes in the goose embryo transcriptome during feather development. RNA-Sequencing (RNA-Seq) was used to find the transcriptome profiles of feather follicles from three stages of embryonic dorsal skin at embryonic day 13, 18, and 28 (E13, E18, E28). The results showed that 3001, 6634, and 13,780 genes were differently expressed in three stages. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that differentially expressed genes (DEGs) in E13 vs. E18 were significantly mapped into the GO term of extracellular structure organization and the pathway of extracellular matrix (ECM)-receptor interaction. In E18 vs. E28, the top significantly mapped into GO term was the single-organism developmental process; the pathway was also the ECM-receptor interaction. DEGs in E13 vs. E28 were significantly mapped into the GO term of the multicellular organismal process and the pathway of cell adhesion molecules. Subsequently, the union of DEGs was categorized by succession cluster into eight profiles, which were then grouped into four ideal profiles. Lastly, the seven genes spatio-temporal expression pattern was confirmed by real-time PCR. Our findings advocate that interleukin 20 receptor subunit alpha (IL20RA), interleukin 6 receptor (IL6R), interleukin 1 receptor type 1 (IL-1R1), Wnt family member 3A (WNT3A), insulin-like growth factor binding protein 3 (IGFBP3), bone morphogenetic protein 7 (BMP7), and secreted-frizzled related protein 2 (SFRP2) might possibly play vital roles in skin and feather follicle development and growth processes. [ABSTRACT FROM AUTHOR]