Nitrogen-Mediated Promotion of Cobalt-Based Oxygen Evolution Catalyst for Practical Anion-Exchange Membrane Electrolysis.

Scarce and expensive iridium oxide is still the cornerstone catalyst of polymer-electrolyte membrane electrolyzers for green hydrogen production because of its exceptional stability under industrially relevant oxygen evolution reaction (OER) conditions. Earth-abundant transition metal oxides used for this task, however, show poor long-term stability. We demonstrate here the use of nitrogen-doped cobalt oxide as an effective iridium substitute. The catalyst exhibits a low overpotential of 240 mV at 10 mA cm-2 and negligible activity decay after 1000 h of operation in an alkaline electrolyte. Incorporation of nitrogen dopants not only triggers the OER mechanism switched from the traditional adsorbate evolution route to the lattice oxygen oxidation route but also achieves oxygen nonbonding (ONB) states as electron donors, thereby preventing structural destabilization. In a practical anion-exchange membrane water electrolyzer, this catalyst at anode delivers a current density of 1000 mA cm-2 at 1.78 V and an electrical efficiency of 47.8 kW-hours per kilogram hydrogen.

Ambient Pressure Drying of Freeze-Cast Ceramics from Aqueous Suspension.

Freeze-casting has been wildly exploited to construct porous ceramics but usually requires costly and demanding freeze-drying (high vacuum, size limit, and supercooled chamber), which can be avoided by the ambient pressure drying (APD) technique. However, applying APD to freeze-cast ceramic based on an aqueous suspension is still challenging due to inert surface chemistry. Herein, a modified APD strategy is developed to improve the drying process of freeze-cast ceramics by exploiting the simultaneous ice etching, ionic cross-linking, and solvent exchange under mild conditions (-10-0 °C, ambient pressure). This versatile strategy is applicable to various ceramic species, metal ions, and freezing techniques. The incorporated metal ions not only enhance liquid-phase sintering, producing ceramics with higher density and mechanical properties than freeze-cast counterparts, but also render customizable coloration and antibacterial property. The cost-/time-efficient APD is promising for mass production and even successive production of large-size freeze-cast ceramics that exceed the size of commercial freeze-dryers.

Nanofabrication and characterization of a grating-based condenser for uniform illumination with hard X-rays.

In the development of full-field transmission X-ray microscopy for basic study in science and technology, a condenser capable of providing intense illumination with high uniformity and stability on tested specimens in order to achieve high-quality images is essential. The latest design of a square-shaped condenser based on diffractive gratings has demonstrated promising uniformity in illumination. This paper describes in more detail the development of such a beam shaper for hard X-rays at 10 keV with regard to its design, manufacture and optical characterization. The effect of the grating profile on the diffracted intensity has been theoretically predicted by numerical simulation using the finite-difference time-domain method. Based on this, the limitations of the grating-based condenser are discussed.

Coordination Mechanism and Bio-Evidence: Reactive γ-Ketoenal Intermediated Hepatotoxicity of Psoralen and Isopsoralen Based on Computer Approach and Bioassay.

Psoralen and isopsoralen are secondary plant metabolites found in many fruits, vegetables, and medicinal herbs. Psoralen-containing plants (Psoralea corylifolia L.) have been reported to cause hepatotoxicity. Herein, we found that psoralen and isopsoralen were oxidized by CYP450s to reactive furanoepoxide or γ-ketoenal intermediates, causing a mechanism-based inhibition of CYP3A4. Furthermore, in GSH-depleted mice, the hepatotoxicity of these reactive metabolites has been demonstrated by pre-treatment with a well-known GSH synthesis inhibitor, L-buthionine-S, Rsulfoxinine (BSO). Moreover, a molecular docking simulation of the present study was undertaken to understand the coordination reaction that plays a significant role in the combination of unstable intermediates and CYP3A4. These results suggested that psoralen and isopsoralen are modest hepatotoxic agents, as their reactive metabolites could be deactivated by H2O and GSH in the liver, which partly contributes to the ingestion of psoralen-containing fruits and vegetables being safe.

Photon nanojet lens: design, fabrication and characterization.

In this paper, a novel nanolens with super resolution, based on the photon nanojet effect through dielectric nanostructures in visible wavelengths, is proposed. The nanolens is made from plastic SU-8, consisting of parallel semi-cylinders in an array. This paper focuses on the lens designed by numerical simulation with the finite-difference time domain method and nanofabrication of the lens by grayscale electron beam lithography combined with a casting/bonding/lift-off transfer process. Monte Carlo simulation for injected charge distribution and development modeling was applied to define the resultant 3D profile in PMMA as the template for the lens shape. After the casting/bonding/lift-off process, the fabricated nanolens in SU-8 has the desired lens shape, very close to that of PMMA, indicating that the pattern transfer process developed in this work can be reliably applied not only for the fabrication of the lens but also for other 3D nanopatterns in general. The light distribution through the lens near its surface was initially characterized by a scanning near-field optical microscope, showing a well defined focusing image of designed grating lines. Such focusing function supports the great prospects of developing a novel nanolithography based on the photon nanojet effect.

Mechanism-based inhibition of CYPs and RMs-induced hepatoxicity by rutaecarpine.

1. Rutaecarpine, a quinolone alkaloid isolated from the unripe fruit of Evodia rutaecarpa, is one of the main active components used in a variety of clinical applications, including the treatment of hypertension and arrhythmia. However, its hepatotoxicity has also been reported in recent years. 2. Reactive metabolites (RMs) play a vital role in drug-induced liver injury. Rutaecarpine has a secondary amine structure that may be activated to RMs. The aim of the study was to investigate the inhibition of rutaecarpine on CYPs and explore the possible relationship between RMs and potential hepatotoxicity. 3. A cell counting kit-8 cytotoxicity assay indicated that rutaecarpine can decrease the primary rat hepatocyte viability, increase lactate dehydrogenase and reactive oxygen species, reduce JC-1, and cause cell stress and membrane damage. The indexes were significantly restored by adding ABT, an inhibitor of CYPs. A cocktail assay showed that CYP1A2, CYP2C9, CYP2C19, CYP2E1 and CYP3A4 can be inhibited by rutaecarpine in human liver microsomes. The IC50 values of CYP1A2 with and without NADPH were 2.2 and 7.4 µM, respectively, which presented a 3.3 shift. The results from a metabolic assay indicated that three mono-hydroxylated metabolites and two di-hydroxylated metabolites were identified and two GSH conjugates were also trapped. 4. Rutaecarpine can inhibit the activities of CYPs and exhibit a potential mechanism-based inhibition on CYP1A2. RMs may cause herb-drug interactions, providing important information for predicting drug-induced hepatotoxicity.

Gold nanopillar arrays as biosensors fabricated by electron beam lithography combined with electroplating.

We report our work on the development of subwavelength gold pillar arrays as local surface plasmonic (LSP) resonators for sensor applications. These arrays are fabricated by electron beam lithography combined with electroplating. The conical shape, instead of flat one, on the top of Au pillars, induced by uneven current density in the plating, may affect the LSP resonance (LSPR). This paper aims to carry out a systematic study of LSPR behavior in nanopillar arrays with both flat and conical shapes on the top, trying to prove the feasibility of the developed nanoprocess. Both numerical simulations by the finite-difference time-domain (FDTD) method and experimental characterization on fabricated LSP resonators for reflectance spectra were carried out. Our experiments indicate that the fabricated nanopillar arrays in Au demonstrate the promising capability of refractive index sensing with sensitivity of 270 nm/refractive index unit. FDTD simulation of electric field density in the gap between pillars reveals the correlation between the resonant absorption of the incident light and the standing waves of localized surface plasmon polaritons in the gaps of the pillar array, despite the conical shape of the pillars. Moreover, it was discovered that the resonant absorption becomes stronger when the light incident angle is increased. The proposed nanoprocess for pillar arrays should possess great prospects for manufacturing Au pillars with high aspect ratio for achieving higher sensitivity at an economical cost.

Simulation and experimental study of aspect ratio limitation in Fresnel zone plates for hard-x-ray optics.

For acquiring high-contrast and high-brightness images in hard-x-ray optics, Fresnel zone plates with high aspect ratios (zone height/zone width) have been constantly pursued. However, knowledge of aspect ratio limits remains limited. This work explores the achievable aspect ratio limit in polymethyl methacrylate (PMMA) by electron-beam lithography (EBL) under 100 keV, and investigates the lithographic factors for this limitation. Both Monte Carlo simulation and EBL on thick PMMA are applied to investigate the profile evolution with exposure doses over 100 nm wide dense zones. A high-resolution scanning electron microscope at low acceleration mode for charging free is applied to characterize the resultant zone profiles. It was discovered for what we believe is the first time that the primary electron-beam spreading in PMMA and the proximity effect due to extra exposure from neighboring areas could be the major causes of limiting the aspect ratio. Using the optimized lithography condition, a 100 nm zone plate with aspect ratio of 15/1 was fabricated and its focusing property was characterized at the Shanghai Synchrotron Radiation Facility. The aspect ratio limit found in this work should be extremely useful for guiding further technical development in nanofabrication of high-quality Fresnel zone plates.

Prevalence of high-risky behaviors in transmission of HIV among high school and college student MSM in China: a meta-analysis.

BACKGROUND: The aim of this study was to investigate the prevalence of high-risky behaviors, such as unprotected anal intercourse (UAI) in the last 6 months, condom using in their last homosexual anal intercourse, No. of male partners in the last 6 months among high school and college male students who have sex with men (MSM) in China. METHODS: The relevant trials were retrieved up to June 2015 from several public databases, and a meta-analysis was conducted according to the published studies. The estimated rate and its 95 % confidence intervals (CI) of the relevant indexes among high school and college student MSM were collected and calculated using a fixed-effects model (the Mantel-Haenszel method) or a random-effects model (the DerSimonian and Laird method) when appropriate. RESULTS: A total of 15 studies (18 research data), including 3297 student MSM, were performed in this meta-analysis. The overall results showed that the rate of student MSM who reported having had UAI in the last 6 months was 65.2 % (95 % CI = 60.2 % to 70.1 %), the prevalence of student MSM having more than one male partner in the last 6 months was 58.2 % (95 % CI = 51.1 % to 65.4 %), the rate of student MSM who reported using a condom in their last homosexual anal intercourse experience was 57.5 % (95 % CI = 49.8 % to 65.1 %), the prevalence of student MSM who were infected with HIV was 3.8 % (95 % CI = 2.5 % to 5.1 %), and the rate of student MSM who were infected with syphilis was 4.6 % (95 % CI = 3.8 % to 5.4 %). CONCLUSIONS: There are high UAI prevalence and low condom using rate in the last homosexual anal intercourse experience among high school and college student MSM in China, and corresponding control measures for this group and more effective health education of student MSM are required to prevent HIV or sexually transmitted diseases from spreading to the general population.

Prevalence of unprotected anal intercourse in men who have sex with men recruited online versus offline: a meta-analysis.

BACKGROUND: Men who have sex with men (MSM) are a high risk population for human immunodeficiency virus (HIV) infection. Our study aims to find whether MSM who were recruited online had a higher prevalence of self-reported unprotected anal intercourse (UAI) than those who were recruited offline. METHODS: A meta-analysis was conducted from the results of published studies. The analysis was stratified by the participants' geographic location, the sample size and the date of the last reported UAI. RESULTS: Based on fourteen studies, MSM who were recruited online (online-based group) reported that 33.9% (5,961/17,580) of them had UAI versus 24.9% (2,700/10,853) of MSM who were recruited offline (offline-based group). The results showed that it is more likely for an online-based MSM group to have UAI with male partners than an offline-based MSM group [odds ratio (OR) = 1.35, 95% CI = 1.13-1.62, P < 0.01]. The subgroup analysis results also showed that the prevalence of UAI was higher in the European subsample (OR = 1.38, 95% CI = 1.17-1.63, P < 0.01) and in sample sizes of more than 500 individuals (OR = 1.32, 95% CI = 1.09-1.61, P < 0.01) in the online group compared to the offline group. The prevalence of UAI was also significantly higher when the time of the last UAI was during the last 3 or more months (OR = 1.40, 95% CI = 1.13-1.74, P < 0.05) in the online group compared to the offline group. A sensitivity analysis was used to test the reliability of the results, and it reported that the results remained unchanged and had the same estimates after deleting any one of the included studies. CONCLUSIONS: A substantial percentage of MSM were recruited online, and they were more inclined to engage in UAI than MSM who were recruited offline. Targeted interventions of HIV prevention programs or services are recommended when designing preventive interventions to be delivered via the Internet.

Adjustment of segmental rotations to achieve both racket speed and accuracy at various impact heights during a two-handed backhand stroke.

This study investigated the influence of impact height and competitive level on racket speed and stroke accuracy by analysing segmental angular kinematics under a random ball condition. High- (HQ, n = 7) and low-quality (LQ, n = 7) groups were determined by k-means clustering of the ratio of ball landing in the target (accuracy) and racket speed decrease. HQ showed higher accuracy (48.3% vs. 32.4%), less speed decrease at lower impact heights (-4.4% vs. -10.3%) and better competitive level ranking [median (1st-3rd quartiles); 4 (2-7)] than LQ [10 (8-13)]. HQ produced greater racket speed (24.4 vs. 21.6 m/s), especially with a notable horizontal velocity (23.8 vs. 20.8 m/s) of the racket at lower impact height, which was attributed to the central role of greater angular velocity of pelvis and thorax in the hitting direction. Both groups showed similar adjustment mechanisms that due to the decrease in angular velocity of pelvis, players increased the relative rotation angle between pelvis and thorax to maintain angular velocity of thorax when transitioning from low to high impact heights. Our findings suggest that players should emphasise the coordination between pelvic and thoracic rotations according to impact heights to maintain racket speed while controlling ball landing position.

Highly Regular Layered Structure via Dual-Spatially-Confined Alignment of Nanosheets Enables High-Performance Nanocomposites.

Assembling ultrathin nanosheets into layered structure represents one promising way to fabricate high-performance nanocomposites. However, how to minimize the internal defects of the layered assemblies to fully exploit the intrinsic mechanical superiority of nanosheets remains challenging. Here, a dual-scale spatially confined strategy for the co-assembly of ultrathin nanosheets with different aspect ratios into a near-perfect layered structure is developed. Large-aspect-ratio (LAR) nanosheets are aligned due to the microscale confined space of a flat microfluidic channel, small-aspect-ratio (SAR) nanosheets are aligned due to the nanoscale confined space between adjacent LAR nanosheets. During this co-assembly process, SAR nanosheets can flatten LAR nanosheets, thus reducing wrinkles and pores of the assemblies. Benefiting from the precise alignment (orientation degree of 90.74%) of different-sized nanosheets, efficient stress transfer between nanosheets and interlayer matrix is achieved, resulting in layered nanocomposites with multiscale mechanical enhancement and superior fatigue durability (100 000 bending cycles). The proposed co-assembly strategy can be used to orderly integrate high-quality nanosheets with different sizes or diverse functions toward high-performance or multifunctional nanocomposites.

Composition analysis of Compound Shenhua Tablet, a seven-herb Chinese medicine for IgA nephropathy: evaluation of analyte-capacity of the assays.

Compound Shenhua Tablet, a medicine comprising seven herbs, is employed in treating IgA nephropathy. This study aimed to meticulously analyze its chemical composition. Based on a list of candidate compounds, identified through extensive literature review pertinent to the tablet's herbal components, the composition analysis entailed the systematic identification, characterization, and quantification of the constituents. The analyte-capacity of LC/ESI-MS-based and GC/EI-MS-based assays was evaluated. The identified and characterized constituents were quantified to determine their content levels and were ranked based on the constituents' daily doses. A total of 283 constituents, classified into 12 distinct categories, were identified and characterized in the Compound Shenhua Tablet. These constituents exhibited content levels of 1-10 982 µg·g-1, with daily doses of 0.01-395 µmol·d-1. The predominant constituents, with daily doses of ≥ 10 µmol·d-1, include nine organic acids (citric acid, quinic acid, chlorogenic acid, cryptochlorogenic acid, gallic acid, neochlorogenic acid, isochlorogenic acid C, isochlorogenic acid B, and linoleic acid), five iridoids (specnuezhenide, nuezhenoside G13, nuezhenidic acid, secoxyloganin, and secologanoside), two monoterpene glycosides (paeoniflorin and albiflorin), a sesquiterpenoid (curzerenone), a triterpenoid (oleanolic acid), and a phenylethanoid (salidroside). Additionally, there were 83, 126, and 55 constituents detected in the medicine with daily doses of 1-10, 0.1-1, and 0.01-0.1 µmol·d-1, respectively. The combination of the LC/ESI-MS-based and GC/EI-MS-based assays demonstrated a complementary relationship in their analyte-capacity for detecting the constituents present in the medicine. This comprehensive composition analysis establishes a solid foundation for further pharmacological research on Compound Shenhua Tablet and facilitates the quality evaluation of this complex herbal medicine.

Hierarchical and reconfigurable interfibrous interface of bioinspired Bouligand structure enabled by moderate orderliness.

Introducing natural Bouligand structure into synthetics is expected to develop high-performance structural materials. Interfibrous interface is critical to load transfer, and mechanical functionality of bioinspired Bouligand structure yet receives little attention. Here, we propose one kind of hierarchical and reconfigurable interfibrous interface based on moderate orderliness to mechanically reinforce bioinspired Bouligand structure. The interface imparted by moderate alignment of adaptable networked nanofibers hierarchically includes nanofiber interlocking and hydrogen-bonding (HB) network bridging, being expected to facilitate load transfer and structural stability through dynamic adjustment in terms of nanofiber sliding and HB breaking-reforming. As one demonstration, the hierarchical and reconfigurable interfibrous interface is constructed based on moderate alignment of networked bacterial cellulose nanofibers. We show that the resultant bioinspired Bouligand structural material exhibits unusual strengthening and toughening mechanisms dominated by interface-microstructure multiscale coupling. The proposed interfibrous interface enabled by moderate orderliness would provide mechanical insight into the assembly of widely existing networked nanofiber building blocks toward high-performance macroscopic bioinspired structural assemblies.

[Prevalence of HIV among men who have sex with men of inland high school and college students in China: a meta-analysis].

OBJECTIVE: To analyze the prevalence of HIV among men who have sex with men (MSM) of inland high school and college students in China, and to analyze the differences between sample size, sampling methods and study period. METHODS: Electronic search strategy was carried out, using WanFang database, China Journal Full-text database, VIP database, CBM and PubMed database to collect data on high school and college students, HIV and MSM, among residents in China. Fixed effects model or random effects model was employed according to statistical tests for homogeneity. Publication bias was assessed by funnel plot. RESULTS: Ten studies were selected with a total of 2014 students-MSM and 106 HIV infected. The overall prevalence of HIV was 4.6% (95% CI 2.9%-6.3%). The prevalence of HIV was stratified by factors as sample size, sampling methods and study period of the study. The pooled prevalence rates of HIV were as follows: 4.7% (95% CI 2.5%-7.0%) and 4.7% (95% CI 1.9%-7.4%) for sample size > 200 and sample size 200, 6.1% (95% CI 3.0%-9.1%) and 2.9% (95% CI 1.7%-4.1%) for snow sampling and non-snow sampling, respectively. The pooled prevalence of HIV were 3.0% (95% CI 1.7%-4.2%) in the study year of 2005-2007 and 6.0% (95% CI 3.1%-9.0%) in 2008-2010, respectively. The pooled prevalence of HIV was higher in snow sampling than non-snow sampling, in the study year of in 2008-2010 than in 2005-2007. CONCLUSION: The prevalence of HIV among MSM of inland high school and college students in China was higher than general population.

Chaperonin co-expression and chemical modification enables production of active microbial transglutaminase from E. coli cytoplasm.

Microbial transglutaminase (MTG) is a usable enzyme for biomacromolecule modification. In the present study, a "molecular chaperonin" strategy was developed to produce MTG in E. coli cytoplasm with high expression level and a "small molecule-mediated chemical modification" strategy was adopted to strip propeptide chaperonin efficiently during purification. Propeptide (Pro) was expressed separately as a chaperonin to facilitate MTG expression in E. coli cytoplasm with a yield up to 300 mg or about 9 kU from 1 L fed-batch culture. Furthermore, small molecular chemicals were applied to interfere the interaction between MTG and Pro. Chemical acetylation was identified as a suitable method to strip Pro resulting in pure MTG with high specific activity up to 49.6 U/mg. The purified acetylated MTG was characterized by MS analysis. The deconvoluted mass and Peptide Sequence Tags analysis confirmed acetylation on amino groups of MTG protein. Finally, the applications of obtained MTG were demonstrated via protein polymerization of bovine serum albumin and PEGylation of human interferon-α2b. Our method provides MTG with high purity and specific activity as well as unique merit with masked amino groups thus avoiding self-polymerization and cross-linking between MTG and substrates.

Scalable Manufacturing of Mechanical Robust Bioinspired Ceramic-Resin Composites with Locally Tunable Heterogeneous Structures.

Lightweight structural materials with a unique combination of high stiffness, strength, toughness, and hardness, are highly desired yet challenging to be artificially fabricated. Biological structural materials, on the other hand, ingeniously integrate multiple mutually exclusive mechanical properties together relying on their hierarchically heterogeneous structures bonded with gradient interfaces. Here, a scalable bottom-up approach combining continuous nanofiber-assisted evaporation-induced self-assembly with laminating, pressure-less sintering and resin infiltration is reported to fabricate bioinspired heterogeneous ceramic-resin composites with locally tunable microstructure to fulfill specific properties. A gradient interlayer is introduced to provide a gradual transition between adjacent heterogeneous layers, effectively alleviating their property mismatch. The optimized heterogeneous nacre-like composite, as a demonstration, exhibits an attractive combination of low density (≈2.8 g cm-3 ), high strength (≈292 MPa), toughness (≈6.4 MPa m1/2 ), surface hardness (≈1144 kgf mm-2 ) and impact-resistance, surpassing the overall performance of engineering alumina. This material-independent approach paves the way for designing advanced bioinspired heterogeneous materials for diverse structural and functional applications.

Mechanically robust bamboo node and its hierarchically fibrous structural design.

Although short bamboo nodes function in mechanical support and fluid exchange for bamboo survival, their structures are not fully understood compared to unidirectional fibrous internodes. Here, we identify the spatial heterostructure of the bamboo node via multiscale imaging strategies and investigate its mechanical properties by multimodal mechanical tests. We find three kinds of hierarchical fiber reinforcement schemes that originate from the bamboo node, including spatially tightened interlocking, triaxial interconnected scaffolding and isotropic intertwining. These reinforcement schemes, built on porous vascular bundles, microfibers and more-refined twist-aligned nanofibers, govern the structural stability of the bamboo via hierarchical toughening. In addition, the spatial liquid transport associated with these multiscale fibers within the bamboo node is experimentally verified, which gives perceptible evidence for life-indispensable multidirectional fluid exchange. The functional integration of mechanical reinforcement and liquid transport reflects the fact that the bamboo node has opted for elaborate structural optimization rather than ingredient richness. This study will advance our understanding of biological materials and provide insight into the design of fiber-reinforced structures and biomass utilization.

High-accuracy tennis players linearly adjust racket impact kinematics according to impact height during a two-handed backhand stroke.

We hypothesised that high-accuracy players more linearly coordinate racket kinematics with impact heights under random height conditions than low-accuracy players. We compared the adjustments of racket kinematics according to impact height between high- and low-accuracy players. Fourteen male tennis players hit the incoming balls with a two-handed backhand at different impact heights (21-108% of body height) to a target area. The cluster analysis on accuracy divided participants into high- (n = 7, 48.6 ± 2.4%) and low- (n = 7, 32.4 ± 4.8%) accuracy groups. Most of the high-accuracy players linearly decreased the horizontal velocity, increased the vertical velocity, and increased the face angle of racket (R2 = 0.42, 0.36, 0.66) as impact heights increased, while the low-accuracy group only linearly increased face angle (R2 = 0.46) but not linearly adjusted horizontal and vertical velocities (R2 = 0.02, 0.14). The linearities between horizontal velocity and face angle and between vertical velocity and face angle in high-accuracy group (R2 = 0.40, 0.26) were significantly stronger than those in low-accuracy group (R2 = 0.07, 0.08). We found that the high-accuracy players coordinate more racket kinematics and adopt a set of consistent solutions of adjustment according to impact heights. We suggest that players linearly adjust the velocities and the face angles of rackets according to impact heights when prioritising the accuracy.

Reconstructing a plasmonic metasurface for a broadband high-efficiency optical vortex in the visible frequency.

Metasurfaces consisting of a two-dimensional metallic nano-antenna array are capable of transferring a Gaussian beam into an optical vortex with a helical phase front and a phase singularity by manipulating the polarization/phase status of light. This miniaturizes a laboratory scaled optical system into a wafer scale component, opening up a new area for broad applications in optics. However, the low conversion efficiency to generate a vortex beam from circularly polarized light hinders further development. This paper reports our recent success in improving the efficiency over a broad waveband at the visible frequency compared with the existing work. The choice of material, the geometry and the spatial organization of meta-atoms, and the fabrication fidelity are theoretically investigated by the Jones matrix method. The theoretical conversion efficiency over 40% in the visible wavelength range is worked out by systematic calculation using the finite difference time domain (FDTD) method. The fabricated metasurface based on the parameters by theoretical optimization demonstrates a high quality vortex in optical frequencies with a significantly enhanced efficiency of over 20% in a broad waveband.