Well-posedness of a multidimensional free boundary problem modelling the growth of nonnecrotic tumors

In this paper we study a free boundary problem modelling the growth of nonnecrotic tumors. The main trait of this free boundary problem is that it is essentially multidimensional, so that its well-posedness is hard to establish by using the usual methods in the classical theory of free boundary problems. In this paper we use the functional analysis method based on the theory of analytic semigroups to prove that this problem has a unique local solution in suitable function spaces. Continuous dependence of the solution on the initial data and regularities of the solution can also be easily obtained by using the argument of this paper.     

Extrinsic base surface-passivated dual-emitter heterojunction phototransistors

N–p–n InGaP/GaAs Dual-Emitter HPTs (DEHPTs) with and without extrinsic base surface passivation were fabricated to investigate the influence of the surface leakage on the device’s optical performance. There are four operating regions appearing in the output characteristics of DEHPTs under illumination: negative-saturation, negative-tuning, positive-tuning and positive-saturation regions. The InGaP-passivated DEHPT (P-DEHPT), i.e. DEHPT with the extrinsic base surface passivated by InGaP, exhibits the maximum optical gains of 46.57, 46.86 and 47.39 while the non-passivated one (NP-DEHPT) shows ones of 32.02, 33.55 and 33.57 for optical powers of 8.62, 13.2 and 17.5 μW, respectively. However, the NP-DEHPT exhibits the larger peak gain-tuning efficiencies of 37.35, 41.03 and 44.10 compared to 12.76, 13.72 and 16.01 V ⁻¹ for the P-DEHPT for optical powers of 8.62, 13.2 and 17.5 μW, respectively. The better tuning efficiency makes the NP-DEHPT a possible low optical power optoelectronic application.     

A study of the polymerization of styrene initiated by K-THF-GIC system

In this paper, the polymerization of styrene initiated by potassium (K)-tetrahydrofuran (THF)-graphite intercalation compound (GIC) (K-THF-GIC) was studied. The mechanism of the polymerization was determined to be anionic polymerization according to its characteristics. The effect of the concentration of the initiator and monomer was studied. It was found that the polymerization mainly occurred on the surface and edge of the intercalated graphite. It was also shown that the polarity of solvent has little effect on the polymerization yield in this system.     

A high-gain porous silicon metal–semiconductor–metal photodetector through rapid thermal oxidation and rapid thermal annealing

2 tungsten lamp at 1.83 mA excited by a 0.85-mW 675-nm laser diode. We also demonstrate that the dark current could be greatly reduced through rapid thermal oxidation and rapid thermal annealing. Received: 4 August 1997/Accepted: 28 May 1998     

Briaexcavatolides X-Z, three new briarane-related derivatives from the gorgonian coral Briareum excavatum

Three new polyoxygenated briarane-type diterpenoids, briaexcavatolides X-Z (1-3), have been isolated from the gorgonian coral Briareum excavatum. The structures, including the relative configurations of briaranes 1-3, were elucidated by spectroscopic methods, particularly in 1D and 2D NMR experiments. The configuration of briarane 1 was further supported by molecular mechanics calculations.     

Chiral Cu(II) complex catalyzed enantioselective addition of phenylacetylene to N-aryl arylimines

Chiral tridentate N-tosylated aminoimine ligands were used in the Cu(II)-catalyzed enantioselective addition of phenylacetylene to N-aryl arylimines, affording products up to 92% ee.     

Xyloketal H from the mangrove endophytic fungus Xylaria sp. 2508

(3R*,3aR*,9aR*)-3,9a-Dimethyl-2,3,3a,9a-tetrahydro-4H-furo[2,3-b]chromene-5,7-diol (xyloketal H), a representative of a new family of xyloketals, was isolated from the marine-derived mangrove fungus Xylaria sp. 2508. Its structure was elucidated by spectroscopic data and single-crystal X-ray diffraction analysis. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1051–1052, June, 2006.     

稀土发光材料在固体白光LED照明中的应用

固体白光发光二极管将成为21世纪新一代的节能光源. 要实现白光发射的重要途径之一是利用稀土发光材料的荧光转换技术, 把InGaN半导体管芯发射的460 nm蓝光或400 nm近紫外光转换成白光. 分别就这两种管芯报道了我们研制的发射蓝、绿、黄、红等不同颜色的稀土发光材料： YAG：Ce, Ca1-xSrxS：Eu^2＋, Ga2S3：Eu^2＋, MGa2S4：Eu^2＋（M=Ca, Sr, Ba）, SrGa^2＋xS4＋y：Eu^2＋, （Ca1-xSrx）Se：Eu^2＋, SrLaGa3S6O：Eu^2＋, （M1, M2）10（PO4）6X2, （M1=Ca, Sr, Ba; M2=Eu, Mn; X=F, Cl, Br）, NaEu0.92Sm0.08（MoO4）2, 并报道了由它们制成的白光发光二极管的色坐标、相关色温和显色指数等参数.     

对甲苯磺酸铜的电化学表征

合成了对甲苯磺酸铜,用X光单晶衍射确定了其结构.实验结果表明,该盐容易脱除全部结晶水,在空气中不潮解.分别测定了对甲苯磺酸铜(Cu(p-OTs)2)在H2O、CH3OH和DMF中的电化学参数.实验结果表明Cu(p-OTs)2在不同溶剂中的反应机理各异. Cu(II)的电化学还原在H2O中是分两步进行,而在CH3OH和DMF中的电化学还原是一步两电子过程.对实验结果进行了分析讨论.     

ZnGA-MMT catalyzed the copolymerization of carbon dioxide with propylene oxide

Zinc glutarate (ZnGA) synthesized from zinc oxide and glutarate acid was dispersed on the surface of acid-treated montmorillonite (MMT) in quinoline to prepare ZnGA-MMT catalyst. The results of X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) measurements indicated that the ZnGA on the surface of acid-treated MMT had the same crystalline structure as pure ZnGA. Copolymerization between CO₂ and propylene oxide (PO) was carried out under optimized reaction conditions using ZnGA-MMT catalyst, consequently giving poly(propylene carbonate) (PPC) with high molecular weight in a very high yield (115.2 g polymer per gram of ZnGA). The obtained PPCs were investigated using ¹³C NMR and FTIR spectra, showing a completely alternating structure. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) examinations showed the PPCs with a high transition temperature of 38 °C and a very high decomposition temperature (>250 °C) due to the presence of MMT residual in polymer.