SHPF-TCR联合控制补偿系统的研究

针对有源电力滤波器无法动态补偿无功功率,无源滤波器补偿产生相移的问题,提出一种晶闸管控制电抗器与并联混合电力滤波器(SHPF-TCR)联合补偿控制系统。SHPF由小容量有源电力滤波器和五次LC单调谐滤波器构成以补偿系统谐波,调谐滤波器和TCR形成并联型无源滤波器以补偿系统无功。将解耦控制用于电流跟踪和电压调节,引入PI控制器消除系统稳态误差。该SHPF-TCR联合控制能够有效的降低APF容量,消除系统谐振,稳定性好,动态响应速度快。实验及仿真结果证明了所提出结构和控制方法可以很好地进行谐波和无功的综合补偿。     

Drop printing of pharmaceuticals: Effect of molecular weight on PEG coated‐naproxen/PEG 3350 solid dispersions

Solid dispersions have been used to enhance the bioavailability of poorly water‐soluble active pharmaceutical ingredients (APIs). However, the solid‐state phase, compositional uniformity, and scale‐up problems are issues that need to be addressed. To allow for highly controllable products, the drop printing (DP) technique can provide precise dosages and predictable compositional uniformity of APIs in two‐/three‐dimensional structures. DP was used to prepare naproxen (NAP)/polyethylene glycol 3350 (PEG 3350) solid dispersions with PEG coatings of different molecular weights (MWs). A comparison of moisture‐accelerated crystallization inhibition by different PEG coatings was assessed. Scanning electron microscopy, second harmonic generation microscopy, and differential scanning calorimetry analysis were performed to characterize the morphology and quantify the apparent crystallinity of NAP within the solid dispersions. Thermogravimetric analysis was employed to measure the water content within each sample. The results suggest that the moisture‐accelerated crystallization inhibition capability of the PEG coatings increased with increasing MW of the PEG coating. Besides, to demonstrate the flexibility of DP technology on manufacturing formulation, multilayer tablets with different PEG serving as barrier layers were also constructed, and their dissolution behavior was examined. By applying DP and appropriate materials, it is possible to design various carrier devices used to control the release dynamics of the API. © 2015 American Institute of Chemical Engineers AIChE J, 61: 4502–4508, 2015     

Multilayer‐coated NPK compound fertilizer hydrogel with controlled nutrient release and water absorbency

A novel trilayered controlled‐release nitrogen, phosphorous, and potassium (NPK) fertilizer hydrogel was prepared by dipping the NPK fertilizer granules sequentially in 7% w v^?1 poly(vinyl alcohol) (PVA) and 2% w v^?1 chitosan (CS) solutions and then cross‐linking the CS layer (cross‐CS) via glutaraldehyde vapor deposition. Different NPK fertilizer hydrogels were then synthesized by inverse suspension polymerization of the dried PVA/cross‐CS bilayer‐coated fertilizer granules in various molar ratios of acrylamide (AM) and acrylic acid (AA) monomers, and polymerization with varying molar ratios of ammonium persulfate, N,N,N′,N′‐tetramethylethylenediamine and N,N′‐methylenebisacrylamide (N‐MBA). The water dissolution time of the obtained PVA/cross‐CS/poly (AA‐co‐AM) trilayer‐coated NPK fertilizer hydrogel granules was prolonged, while the water absorbency increased with increasing AA contents, and decreased with increasing N‐MBA contents in the outer poly(AA‐co‐AM) coating. The optimal trilayer‐coated NPK fertilizer hydrogel obtained released 84 ± 18, 63 ± 12, and 36 ± 15% of the N, P, and K nutrients, respectively, after a 30‐day immersion in water. The release phenomena of the N, P, and K nutrients of the fertilizer hydrogel obeyed both the Korsmeyer‐Peppas and Ritger‐Peppas models with a pseudo‐Fickian diffusion mechanism. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41249.     

一种LC-VCO 1/f3相位噪声优化方法

建立了差分互补型电感电容压控振荡器(LC-VCO)的等效分析模型.采用有效截止频率厂T.e.来表征MOS管的充放电能力,结合振荡器起振后共模输出电压下降的现象,提出了优化1/f3相位噪声的方法.采用该方法并结合跨导效率gm/ID设计方法,实现了LC-VCO 1/f3相位噪声的优化,并在0.18 μm CMOS工艺上获得验证.结果表明,该优化方法可以使频偏在1 kHz以内的相位噪声改善2～3 dB,可用于开环LC-VCO作为本振的低功耗无线收发机及高性能晶体振荡器的电路设计中.     

Photo-Doped Active Electrically Controlled Terahertz Modulator

We demonstrate an electric-controlled terahertz (THz) modulator which can be used to realize amplitude modulation of terahertz waves with slight photo-doping. The THz pulse transmission was efficiently...     

Double‐Walled Au Nanocage/SiO2 Nanorattles: Integrating SERS Imaging,Drug Delivery and Photothermal Therapy

In this work, a novel type of nanomedical platform, the double‐walled Au nanocage/SiO₂ nanorattle, is successfully fabricated by combining two “hollow‐excavated strategies”—galvanic replacement and “surface‐protected etching”. The rational design of double‐walled nanostructure based on gold nanocages (AuNCs) and hollow SiO₂ shells functionalized respectively with p‐aminothiophenol (pATP) and Tat peptide simultaneously renders the nanoplatforms three functionalities: 1) the whole nanorattle serves as a high efficient drug carrier thanks to the structural characteristics of AuNC and SiO₂ shell with hollow interiors and porous walls; 2) the AuNC with large electromagnetic enhancement acts as a sensitive surface‐enhanced Raman scattering (SERS) substrate to track the internalization process of the nanorattles by human MCF‐7 breast cancer cells, as well as an efficient photothermal transducer for localized hyperthermia cancer therapy due to the strong near‐infrared absorption; 3) Tat‐functionalized SiO₂ shell not only improves biocompatibility and cell uptake efficiency resulting in enhanced anticancer efficacy but also prevents the AuNCs from aggregation and provides the stability of AuNCs so that the SERS signals can be used for cell tracking in high fidelity. The reported chemistry and the designed nanostructures should inspire more interesting nanostructures and applications.     

Remotely Controlled Red Blood Cell Carriers for Cancer Targeting and Near‐Infrared Light‐Triggered Drug Release in Combined Photothermal–Chemotherapy

Red blood cells (RBCs), the “innate carriers” in blood vessels, are gifted with many unique advantages in drug transportation over synthetic drug delivery systems (DDSs). Herein, a tumor angiogenesis targeting, light stimulus‐responsive, RBC‐based DDS is developed by incorporating various functional components within the RBC platform. An albumin bound near‐infrared (NIR) dye, together with a chemotherapy drug doxorubicin, is encapsulated inside RBCs, the surfaces of which are modified with a targeting peptide to allow cancer targeting. Under stimulation by an external NIR laser, the membrane of the RBCs would be destroyed by the light‐induced photothermal heating, resulting in effective drug release. As a proof of principle, RBC‐based cancer cell targeted drug delivery and light‐controlled drug release is demonstrated in vitro, achieving a marked synergistic therapeutic effect through the combined photothermal–chemotherapy. This work presents a novel design of smart RBC carriers, which are inherently biocompatible, promising for targeted combination therapy of cancer.     

Modular and Versatile Spatial Functionalization of Tissue Engineering Scaffolds through Fiber‐Initiated Controlled Radical Polymerization

Native tissues are typically heterogeneous and hierarchically organized, and generating scaffolds that can mimic these properties is critical for tissue engineering applications. By uniquely combining controlled radical polymerization (CRP), end‐functionalization of polymers, and advanced electrospinning techniques, a modular and versatile approach is introduced to generate scaffolds with spatially organized functionality. Poly‐ε‐caprolactone is end functionalized with either a polymerization‐initiating group or a cell‐binding peptide motif cyclic Arg‐Gly‐Asp‐Ser (cRGDS), and are each sequentially electrospun to produce zonally discrete bilayers within a continuous fiber scaffold. The polymerization‐initiating group is then used to graft an antifouling polymer bottlebrush based on poly(ethylene glycol) from the fiber surface using CRP exclusively within one bilayer of the scaffold. The ability to include additional multifunctionality during CRP is showcased by integrating a biotinylated monomer unit into the polymerization step allowing postmodification of the scaffold with streptavidin‐coupled moieties. These combined processing techniques result in an effective bilayered and dual‐functionality scaffold with a cell‐adhesive surface and an opposing antifouling non‐cell‐adhesive surface in zonally specific regions across the thickness of the scaffold, demonstrated through fluorescent labelling and cell adhesion studies. This modular and versatile approach combines strategies to produce scaffolds with tailorable properties for many applications in tissue engineering and regenerative medicine.