Microlens arrays prepared via colloidal microsphere templating

<正>A simple and efficient templating method in combination with hot embossing technique is developed for fabricating large-area two-dimensional(2D) microlens arrays(MLAs) with uniform shape.By utilizing a modified microchannel method,a 2D large-area hexagonal close-packed(HCP) array of silica colloidal microspheres is prepared and serves as a template in the following hot embossing treatment to create a polycarbonate(PC) microcavity array.Then,with the obtained PC microcavity structure serving as a mold,a hot embossing process is applied to finally achieve a polymethylmethacrylate(PMMA) MLA.The effect of annealing time during the mold preparation process on the dimensions and shapes of the prepared microlens is investigated.The imaging performances of the prepared PC concave microcavities and PMMA convex microlenses are characterized by carrying out projection experiments.Our method provides a rapid and low cost approach to prepare large-area MLAs.     

Preparation and characterization of silica-silver core-shell structural submicrometer spheres

Dense, uniform and thickness controllable silver layers were successfully coated on the mono-dispersed submicrometer silica spheres to obtain silica-silver core-shell structural spheres. The growth process of nanoscaled silver layer on silica spheres mainly includes two steps, i.e. nanoscaled nuclei formation and controllable layer growth process. The nuclear-growth mechanism is responsible for the deposition processes. The reagent concentrations and reaction time were found to be the key factors for the formation of controllable silver layer. High quality silver layer with dense and uniform structure was verified by transmission electron microscopy, X-ray diffraction and Energy Dispersive X-ray microanalysis.     

In situ atomic force microscopy studies of growth mechanisms and surface morphology of zinc thiourea sulfate crystals

In situ atomic force microscopy (AFM) has been utilized in studies of the growth mechanism on the (100) face of zinc tris (thiourea) sulphate (ZTS) crystals growing from solution. The growth on the (100) face of pure ZTS crystal is mainly controlled by two dimensional (2D) nucleation mechanisms, under which the hillock is formed through layer‐by‐layer growth. It is easier to form 2D nuclei at edge dislocation and the apex of steps. The growth of 2D nucleus is in accord with nucleation‐spreading mode. The growth rate along the 〈010〉 direction is faster than that along 〈001〉 direction, both of which increase firstly and then decrease with the spread of nucleus. The kinetic coefficients of one nucleus have been roughly estimated to be 3.6 × 10⁻⁴ cm/s and 1.8 × 10⁻⁴ cm/s in two directions, while the activation energy E was calculated to be 53.7 kJ/mol and 55.4 kJ/mol, respectively. The 2D nuclei can be generated under lower supersaturation with the addition of EDTA. If there are several hillocks growing together, step bunches will form when the steps moving in the same direction meet each other, while the meeting of steps that move in the inverse direction will result in the separation of steps. The ability of nucleation of edge dislocation outcrops are different even they are close to each other on the same surface. When the nucleus was generated at the edge dislocation sites, it cannot spread speedily until finishes an “incubation period”. Moreover, the detour of microsteps was observed due to the existence of pits. If the microcrystals attached on the surface block the step advancement, or leave the surface or are covered by the macrosteps, the pits are formed. If the macrosteps advanced across the pits, the pits will be covered and the liquid inclusions may form. However, if the microcrystal forming in the pit grow up and expose on the surface, the pit will not be covered by macrosteps. The formation of solid inclusions may be caused by the microcrystals being embedded into the single steps which move layer‐by‐layer.     

High-Resolution Electrochemical Mapping of the Hydrogen Evolution Reaction on Transition-Metal Dichalcogenide Nanosheets

High-resolution scanning electrochemical cell microscopy (SECCM) is used to image and quantitatively analyze the hydrogen evolution reaction (HER) catalytically active sites of 1H-MoS₂ nanosheets, MoS₂, and WS₂ heteronanosheets. Using a 20 nm radius nanopipette and hopping mode scanning, the resolution of SECCM was beyond the optical microscopy limit and visualized a small triangular MoS₂ nanosheet with a side length of ca. 130 nm. The electrochemical cell provides local cyclic voltammograms with a nanoscale spatial resolution for visualizing HER active sites as electrochemical images. The HER activity difference of edge, terrace, and heterojunction of MoS₂ and WS₂ were revealed. The SECCM imaging directly visualized the relationship of HER activity and number of MoS₂ nanosheet layers and unveiled the heterogeneous aging state of MoS₂ nanosheets. SECCM can be used for improving local HER activities by producing sulfur vacancies using electrochemical reaction at the selected region.     

Core–Shell‐Structured CNT@RuO2 Composite as a High‐Performance Cathode Catalyst for Rechargeable Li–O2 Batteries

A RuO₂ shell was uniformly coated on the surface of core CNTs by a simple sol–gel method, and the resulting composite was used as a catalyst in a rechargeable Li–O₂ battery. This core–shell structure can effectively prevent direct contact between the CNT and the discharge product Li₂O₂, thus avoiding or reducing the formation of Li₂CO₃, which can induce large polarization and lead to charge failure. The battery showed a high round‐trip efficiency (ca. 79 %), with discharge and charge overpotentials of 0.21 and 0.51 V, respectively, at a current of 100 mA g_total^?1. The battery also exhibited excellent rate and cycling performance.     

High-throughput absolute quantification of proteins using an improved two-dimensional reversed-phase separation and quantification concatemer (QconCAT) approach

Stable isotope dilution–selective reaction monitoring–mass spectrometry (SID-SRM-MS) has been widely used for the absolute quantitative analysis of proteins. However, when performing the large-scale absolute quantification of proteins from a more complex tissue sample, such as mouse liver, in addition to a high-throughput approach for the preparation and calibration of large amounts of stable-isotope-labelled internal standards, a more powerful separation method prior to SRM analysis is also urgently needed. To address these challenges, a high-throughput absolute quantification strategy based on an improved two-dimensional reversed-phase (2D RP) separation and quantification concatemer (QconCAT) approach is presented in this study. This strategy can be used to perform the simultaneous quantification of hundreds of proteins from mouse liver within one week of total MS measurement time. By using calibrated synthesised peptides from the protein glutathione S-transferase (GST), large amounts of GST-tagged QconCAT internal standards corresponding to hundreds of proteins can be accurately and rapidly quantified. Additionally, using an improved 2D RP separation method, a mixture containing a digested sample and QconCAT standards can be efficiently separated and absolutely quantified. When a maximum gradient of 72 min is employed in the first LC dimension, resulting in 72 fractions, identification and absolute quantification experiments for all fractions can be completed within one week of total MS measurement time. The quantification approach developed here can further extend the dynamic range and increase the analytical sensitivity of SRM analysis of complex tissue samples, thereby helping to increase the coverage of absolute quantification in a whole proteome.

Preparation of low initial expansion temperature expandable graphite and its flame retardancy for LLDPE

To get expandable graphite (EG) flame retardant for Liner Low-Density Polyethylene (LLDPE) with low initial expansion temperature and high dilatability, the effects of various factors on dilatability were investigated including the dosages of oxidant KMnO₄, intercalating reagent H₂SO₄, assistant intercalating reagent acetic acid (HAc) and reaction temperature. Feasible conditions were obtained according to the results of L₉ (3⁴) experiments and single factor experiments. EG with an initial expansion temperature of 160°C and expansion volume of 460 mL g^?1 could be prepared according to the mass ratio of material graphite C: KMnO₄: 100% H₂SO₄: HAc = 1.0: 0.4: 5.0: 1.0 (H₂SO₄ should be diluted to the mass concentration of 75% before the intercalation reaction); the reaction time was 1.0 hour at 25°C. It was found that reaction temperature and H₂SO₄ dosage were the most important influence factors for dilatability. The limiting oxygen index could be improved to 28.1% by adding 30% of the prepared EG to LLDPE, and the synergistic anti-flame capability of 20% EG with 10% Ammonium polyphosphate (APP) (I) can reach to 33.9%. According to thermal gravimetric and differential thermal analysis results, 70% LLDPE /10% APP (I) /20% EG synergistic anti-flame system shows higher residual carbon and thermal stability.      

广义预测控制的鲁棒性机理分析

This paper deeply analyzes the closed-loop nature of GPC in the framework of internal model control (IMC) theory. A new sort of relation lies in the feedback structure so that robust reason can be satisfactorily explained. The result is significant because the previous conclusions are only applied to open-loop stable plant (or model).     

Micelle formation by N-alkyl-N-methylpyrrolidinium bromide in aqueous solution

The micellization of the ionic liquid N-alkyl-N-methylpyrrolidinium bromide (C(n)MPB, n = 12, 14 and 16) in aqueous solutions was investigated by surface tension measurements, electrical conductivity and static luminescence quenching. The effectiveness of the surface tension reduction (Π(cmc)), maximum surface excess concentration (Γ(max)) and the minimum area (A(min)) occupied per surfactant molecule at the air/water interface can be obtained from the surface tension measurements at 25 °C. The critical micelle concentration (cmc) at different temperatures and a series of thermodynamic parameters (ΔG, ΔH and ΔS) of micellization were evaluated from electrical conductivity measurements in the temperature range of 25-45 °C. The thermodynamic parameters show that the micelle formation is entropy-driven at low temperature and enthalpy-driven at high temperature. Furthermore, the micelle aggregation number (N(agg)) of C(n)MPB was calculated according to the Turro-Yekta method through static luminescence quenching and found that N(agg) (49, 55, and 59) increased with the hydrophobic chain length of C(n)MPB.