Wide‐band divide‐by‐2 injection‐locked frequency divider using MOSFET mixers DC‐biased in subthreshold region

A novel wide locking range divide‐by‐2 injection‐locked frequency divider (ILFD) is proposed in the paper and was implemented in the TSMC 0.18‐µm 1P6M CMOS process. The divide‐by‐2 ILFD is based on a cross‐coupled voltage‐controlled oscillator (VCO) with an LC resonator and injection MOSFETs with source voltage coupled from ILFD output, and the injection MOSFET mixer is biased in subthreshold region. At the drain–source bias of 0.9 V, and at the incident power of 0 dBm the locking range of the divide‐by‐2 ILFD is 6.4 GHz; from the incident frequency 3.7 GHz to 10.1 GHz, the percentage is 92.75%. The core power consumption is 16.56 mW. The die area is 0.839 × 0.566 mm². Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis and Photoluminescence of a Novel Green‐Emitting La5Si3O12N:Eu2+ Phosphor

A novel green‐emitting La₅Si₃O₁₂N:Eu²⁺ phosphor has been synthesized with the solid‐state reaction method under the high temperature, high pressure, and reducing atmosphere. This phosphor shows stable Eu²⁺ photoluminescence spectra. No Eu³⁺ line spectra have been found. For the emission band, an abnormal blue shift has been found. Concentration quenching occurs at Eu²⁺ concentration of 4 mol%. The photoluminescence property at high temperature was investigated. The physical mechanisms for blue shift, concentration quenching and thermal quenching were investigated and discussed. The proposed synthesis process could be a suitable method to acquire the stable Eu²⁺ photoluminescence in the trivalent metal cation compounds.     

烧结温度对(Ti, W, Mo, Nb)(C, N)-(Co, Ni)金属陶瓷组织结构和性能的影响

本文以(Ti,W,Mo,Nb)(C,N)-(Co,Ni)基金属陶瓷材料为研究对象,研究烧结温度对金属陶瓷的成分、微观组织和力学性能的影响,初步探讨成分、微观组织与材料强度的关系。研究结果表明：烧结温度对(Ti,W,Mo,Nb)(C,N)-(Co,Ni)基金属陶瓷组织特征有显著的影响;合金的总碳(Ct%)随着烧结温度的提高而降低,当烧结温度达到1490℃时,合金总碳的急剧降低,导致合金组织中出现脱碳相(η相),从而使得合金的硬度(HV₃₀) 、断裂韧性(KIC)和抗弯强度(TRS)降低;1470℃烧结温度下,(Ti,W,Mo,Nb)(C,N)-(Co,Ni)基金属陶瓷合金的硬度(HV₃₀) 、断裂韧性(KIC)和抗弯强度(TRS)的匹配最佳,表现为在实际应用工况下的综合切削性能最优。     

TiO2‐kaolin‐PE composite film: A study based on photocatalytic degradation and biodegradation

A novel photodegradable and biodegradable polyethylene (PE) film was prepared through a melt blending technique, where nano‐TiO₂ and common kaolin were used as the photocatalyst and biodegradable promoter showing improved degradable efficiency of the waste PE. The photo‐degradation of the composite film was investigated by weight loss monitoring, attenuated total reflection–fourier transformed infrared spectroscopy (ATR–FTIR), and scanning electron microscopy. The aerobic biodegradation of the residue films after photodegradation was investigated by analysis of evolved carbon dioxide of films in aquatic test systems according to the international standards (ISO 14852, 1999). The results showed that the weight loss of as‐prepared photo‐ and biodegradable composite film reached 26.8% after 240 h of UV light irradiation. The big cavities formed not only on the film surface but also inside the bulk film, together with the chalking phenomenon taking place. The biodegradation results revealed that the addition of kaolin enhanced the degradation of UV‐light treated TiO₂‐PE films. The prepared PE based composite films showed promising application as novel photo‐biodegradable environment‐harmless materials. In addition, a degradation mechanism for this composite film was also discussed. POLYM. COMPOS., 37:2353–2359, 2016. © 2015 Society of Plastics Engineers     

Iron(III) Chloride Catalyzed Synthesis of Highly Substituted Indolyl‐Tetrahydroquinoline Derivatives by Using Indolylnitroalkene as Dienophiles and Its Application to the Synthesis of Indolo‐Benzonaphthyridine Derivatives

An efficient iron(III) chloride catalyzed synthesis of highly substituted indolyltetrahydroquinoline derivatives from easily available starting materials, including indolylnitroalkenes, substituted anilines and various aldehydes is reported. The reaction utilized strong electron deficient dienophiles like indolylnitroalkene via a Povarov approach. The methodology shows good functional group tolerance and can be used to prepare fused indolo‐benzonaphthyridine derivatives.

     

羰基铁吸收剂的研究进展

隐身技术已成为当代军事技术的重要内容,受到各军事强国前所未有的重视。吸收剂的研究是促进吸波材料发展的重要环节,是研制和提高吸波材料性能的基础。羰基铁吸收剂作为一种典型的磁损耗型吸收剂,是目前最为常用的雷达波吸收剂之一。当前羰基铁吸收剂的研究主要集中在自身的改性以及与其他吸收剂的共混或复合使用上。在简要介绍羰基铁吸收剂和吸波原理的基础上对这些研究进行了归纳分析与总结,并对羰基铁吸收剂的发展趋势进行了讨论。     

Developing laminar morphology in higher‐viscosity‐ratio polyblends by controlling flow fields in a single‐screw extruder

The morphology of high‐density polyethylene (HDPE)/polyamide‐6 (PA‐6) blends with different melt‐shear‐viscosity ratios (VRs), prepared by combining a single‐screw extruder with a convergent die was studied. Two different screw geometries, metering and mixing screws, and three screw speeds, 20, 40 and 60 rpm, were evaluated to investigate their effects on the morphology of extruded ribbons. Two mixing screws with low and high shear intensity, respectively, were used. Both the geometry and speed of screw were found to have an important role in the morphological changes of the blends. In contrast to previous studies, the results shown in this work reveal that it is possible to develop a laminar structure of PA‐6 in an HDPE matrix with a VR larger than one by controlling the flow fields, through appropriately combining the type and shear intensity of the screw with its speed. A well‐developed laminar PA‐6 phase with an aspect ratio of about 100 was obtained under the optimum combination. Copyright © 2004 Society of Chemical Industry     

Microwave permittivity of SiC-Al2O3 composite powder prepared by sol-gel and carbothermal reduction

SiC-Al2O3 composite powder was prepared by sol-gel and carbothermal reduction method. The powder synthesized was characterized by X-ray diffraction（XRD） and scanning electron microscopy（SEM） to confirm the phase formation, and the thermodynamic analysis was performed systematically. Moreover, the variation of its microwave permittivity with different atomic ratio of Al/Si was investigated in the frequency range of 8.2-12.4 GHz. The results show that, the powder obtained consists of spherical particles of 300-400 nm in diameter, which are composed of SiC and Al2O3 microcrystal with the grain size of approximately 45 nm. The results of XRD accord with those of the thermodynamic analysis. It is impossible for Al atoms to dissolve in the lattice of SiC during the carbothermal reduction process. Along with the increase of atomic ratio of Al/Si in the xerogel, the amount of Al2O3 in the powder synthesized increases, which reduces both ε＇, the real part of complex permittivity, and tg δ（ε＂/ε＇）, the dissipation factor, where ε＂ is the imaginary part of complex permittivity.