Periodic solutions for certain non-smooth oscillators by iterated homotopy perturbation method combined with modified Lindstedt-Poincaré technique

In this paper, a new technique is introduced by combining Homotopy perturbation method and modified Lindstedt-Poincaré technique to obtain the periodic solutions of certain non-smooth oscillators. In this technique, homotopy perturbation method is re-written in iterative form to linearize perturbation process by homotopy, and then, the modified Lindstedt-Poincaré method is utilized to obtain next approximation for each iteration step. We realize that this new technique works very well for the whole range of initial amplitudes, and the excellent agreement of the approximate frequencies and periodic solutions with the exact ones has been confirmed and discussed. Only one or two iterations lead to high accuracy of the solutions. The result obtained and comparison with analytical solution and different methods provide confirmation for the validity of the technique.     

Metal-Chelating Nanopolymers for Antibody Purification from Human Plasma

The purification of immunoglobulin G (IgG) from human plasma was performed by using a novel metal-chelated adsorbent with nano size. The non-porous nanoparticles were produced by surfactant free emulsion polymerization of ethylene glycol dimethacrylate (EDMA) and 2-methacryloylamidohistidine (MAH). Then, Cu(II) ions were chelated on the nanoparticles. The nano-poly(EDMA-MAH) nanoparticles were characterized by Fourier transform infrared, scanning electron microscope, atomic force microscope and elemental analysis. The non-porous nanoparticles were spherical form and have 100?C250?nm size distribution. The maximum IgG adsorption capacity of the Cu(II) chelated nanoparticles was found to be 463?mg/g polymer at pH 7.0 in HEPES buffer. Desorption of IgG was performed by 1.0?M NaCl and desorption rate was found to be 97?%. IgG was obtained from human plasma with purity of 94?% (up to 578?mg/g polymer). The non-porous nanoparticles allowed one-step purification of IgG from human plasma.     

Distribution of maximum loss of fractional Brownian motion with drift

In this paper, we find bounds on the distribution of the maximum loss of fractional Brownian motion with $H\ge 1/2$ and derive estimates on its tail probability. Asymptotically, the tail of the distribution of maximum loss over $[0,t]$ behaves like the tail of the marginal distribution at time $t$.     

Hydrogen activation and metal hydride formation trigger cluster formation from supported iridium complexes

The formation of iridium clusters from supported mononuclear iridium complexes in H(2) at 300 K and 1 bar was investigated by spectroscopy and atomic-resolution scanning transmission electron microscopy. The first steps of cluster formation from zeolite-supported Ir(C(2)H(4))(2) complexes are triggered by the activation of H(2) and the formation of iridium hydride, accompanied by the breaking of iridium-support bonds. This reactivity can be controlled by the choice of ligands on the iridium, which include the support.     

Determination of piribedil in pharmaceutical formulations by micellar electrokinetic capillary chromatography

A fast and simple micellar electrokinetic capillary chromatographic method was developed for the analysis of piribedil in pharmaceutical formulations. The effects of buffer concentration, buffer pH, sodium dodecyl sulphate (SDS) concentration, organic modifier, applied voltage and injection time were investigated. Optimum results were obtained with a 50 mM borate buffer at pH 8.0 containing 50 mM SDS by using a fused silica capillary (50 m internal diameter, 72 cm effective length). The sample was injected hydrodynamically for 4 s at 50 mbar pressure and the applied voltage was +30 kV. The detection wavelength was set at 205 nm. Diflunisal was used as an internal standard. The analysis was performed at 25 °C and the total run time was 14 min. The method was suitably validated with respect to linearity range, limit of detection and quantification, precision, accuracy, specificity and robustness. The linear calibration range was 5–100 g mL^–1 and the limit of detection was determined as 1 g mL^–1. The method developed was successfully applied to the determination of piribedil in pharmaceutical formulations. The results were compared with a spectrophotometric method reported in the literature and no significant difference was found statistically.     

Rock Salt Ni/Co Oxides with Unusual Nanoscale‐Stabilized Composition as Water Splitting Electrocatalysts

The influence of nanoscale on the formation of metastable phases is an important aspect of nanostructuring that can lead to the discovery of unusual material compositions. Here, the synthesis, structural characterization, and electrochemical performance of Ni/Co mixed oxide nanocrystals in the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is reported and the influence of nanoscaling on their composition and solubility range is investigated. Using a solvothermal synthesis in tert ‐butanol ultrasmall crystalline and highly dispersible Ni _x Co_{1? x} O nanoparticles with rock salt type structure are obtained. The mixed oxides feature non‐equilibrium phases with unusual miscibility in the whole composition range, which is attributed to a stabilizing effect of the nanoscale combined with kinetic control of particle formation. Substitutional incorporation of Co and Ni atoms into the rock salt lattice has a remarkable effect on the formal potentials of NiO oxidation that shift continuously to lower values with increasing Co content. This can be related to a monotonic reduction of the work function of (001) and (111)‐oriented surfaces with an increase in Co content, as obtained from density functional theory (DFT+U) calculations. Furthermore, the electrocatalytic performance of the Ni _x Co_{1? x} O nanoparticles in water splitting changes significantly. OER activity continuously increases with increasing Ni contents, while HER activity shows an opposite trend, increasing for higher Co contents. The high electrocatalytic activity and tunable performance of the nonequilibrium Ni _x Co_{1? x} O nanoparticles in HER and OER demonstrate great potential in the design of electrocatalysts for overall water splitting.     

Near‐Infrared Sensitized Photoinduced Atom‐Transfer Radical Polymerization (ATRP) with a Copper(II) Catalyst Concentration in the ppm Range

NIR‐sensitized photoinduced atom‐transfer radical polymerization (ATRP) is possible by using ppm of Cu^II/tris(2‐pyridylmethyl)amine (TPMA) as the catalyst, a polymethine as the photosensitizer, and α‐bromophenylacetate as the alkyl halide initiator. Among the polymethines investigated with cationic, zwitterionic, or anionic structures, only the zwitterionic 2 exhibited sensitization activity under NIR light at room temperature resulting in the formation of polymers with controlled molecular weight characteristics and functionalities. The barbital group placed at the meso‐position of 2 caused the activity in this photo‐ATRP framework. The chain‐end fidelity of the polymers was confirmed by chain extension and block copolymerization experiments. The polymerization system exhibits high photostability under NIR light exposure and irradiation dependency as demonstrated by light on/off experiments.     

3D‐Printed Microrobotic Transporters with Recapitulated Stem Cell Niche for Programmable and Active Cell Delivery

Poor retention rate, low targeting accuracy, and spontaneous transformation of stem cells present major clinical barriers to the success of therapies based on stem cell transplantation. To improve the clinical outcome, efforts should focus on the active delivery of stem cells to the target tissue site within a controlled environment, increasing survival, and fate for effective tissue regeneration. Here, a remotely steerable microrobotic cell transporter is presented with a biophysically and biochemically recapitulated stem cell niche for directing stem cells towards a pre‐destined cell lineage. The magnetically actuated double‐helical cell microtransporters of 76 µm length and 20 µm inner cavity diameter are 3D printed where biological and mechanical information regarding the stem cell niche are encoded at the single‐cell level. Cell‐loaded microtransporters are mobilized inside confined microchannels along computer‐controlled trajectories under rotating magnetic fields. The mesenchymal stem cells are shown retaining their differentiation capacities to commit to the osteogenic lineage when stimulated inside the microswimmers in vitro. Such a microrobotic approach has the potential to enable the development of active microcarriers with embedded functionalities for controlled and precisely localized therapeutic cell delivery.     

基于深度迁移学习的饮食图像识别研究

卷积神经网络(CNN)应用于图像识别具有很大优势,但是需要足够深的网络和大量标签完善的数据集才能发挥其优越性.实际应用中,往往需要应对的是质量差和大小不一的数据集,且受硬件设备限制.为了提高图像识别效率和精度,提出一种基于深度卷积神经网络和迁移学习的识别算法.该算法首先对图像预处理和数据增强,后迁移大样本提取出的特征信息用于CNN特征提取,再接入微调网络对数据集再训练.实验结果显示,本文算法对饮食识别的精度和时间性能均有显著的提高,精确度最高可达98％以上,精度提升最高可达10％以上,时间性能提升幅度最高可达110％.