A Band-Gap Energy Model of the Quaternary Alloy In_(x)Ga_(y)Al_(1−x−y)N using Modified Simplified Coherent Potential Approximation

Based on modification of the simplified coherent potential approximation,a model for the band-gap energy of In_(x)Ga_(y)Al_(1−x−y)N is developed.The parameters of the model are obtained by fitting the experimental band-gap energy of their ternary alloys.It is found that the results agree with the experimental values better than those reported by others,and that the band-gap reduction of In_(x)Ga_(y)Al_(1−x−y)N with increasing In or Ga content is mainly due to enhanced intraband coupling within the conduction band,and separately within the valence band.

High-Efficiency InGaN/GaN Nanorod Arrays by Temperature Dependent Photoluminescence

We report on the photoluminescent characteristics of InGaN/GaN multiple quantum well(MQW)nanorod arrays with high internal quantum efficiency.The InGaN/GaN MQWs are grown by metalorganic chemical vapor deposition on c-plane sapphire substrates,and then the MQW nanorod arrays are fabricated by using inductively coupled plasma etching with self-assembled Ni nanoparticle mask with low-damage etching technique.The typical diameter of the nanorods is from 200 nm to 300 nm and the length is around 800 nm,which almost is dislocation free.At room temperature,an enhancement of 3.1 times in total integrated photoluminescence intensity is achieved from the MQW nanorod arrays,in comparison to that of the as-grown MQW structure.Based on the temperature-dependent photoluminescence measurements,the internal quantum efficiency of the nanorod structure is 59.2%,i.e.,1.75 times of as-grown MQW structure(33.8%).Therefore,the nanorod structure with a significant reduction of defects can be a very promising candidate for highly efficient light emitting devices.

The Formation and Characterization of GaN Hexagonal Pyramids

GaN with hexagonal pyramids is fabricated using the photo-assisted electroless chemical etching method.Defective areas of the GaN substrate are selectively etched in a mixed solution of KOH and K2S2O8 under ultraviolet illumination,producing submicron-sized pyramids.Hexagonal pyramids on the etched GaN with well-defined{1011}facets and very sharp tips are formed.High-resolution x-ray diffraction shows that etched GaN with pyramids has a higher crystal quality,and micro-Raman spectra reveal a tensile stress relaxation in GaN with pyramids compared with normal GaN.The cathodoluminescence intensity of GaN after etching is significantly increased by three times,which is attributed to the reduction in the internal reflection,high-quality GaN with pyramids and the Bragg effect.

In-Plane Optical Anisotropy of a-Plane GaN Film on r-Plane Sapphire Grown by Metal Organic Chemical vapour Deposition

The in-plane optical anisotropic properties of the non-polar a-plane GaN films grown by metal organic chemical vapour deposition are investigated by using polarised photoluminescence(PL),optical transmission and Raman scattering measurements.Through polarised PL and transmission spectra,the in-plane optical anisotropic properties of a-plane GaN film are found,which are attributed to the topmost valance band(atΓpoint)split into three sub-bands under anisotropic strain.The PL spectra also exhibit that the light hole band moves up more rapidly than the spin-orbit crystal-field spilt-off hole band with the increasing in-plane anisotropic compressive strain.Raman scattering spectra under different configurations further indicate the in-plane anisotropy and the hexagonal crystalline structure of these a-plane GaN films.

Raman Scattering Study of In_(x)Ga_(1-x)N Alloys with Low Indium Compositions

In_(x)Ga_(1-x)N alloys with low indium composition x in the range 0.13 ≤ x ≤ 0.23 are systematically studied mainly based on a Raman scattering technique.Scanning electron microscopy and x-ray diffraction results show that our samples can be divided into two groups:pseudomorphic (0.13 ≤ x ≤ 0.16) and relaxed (0.18 ≤ x ≤ 0.23).The prominent enhancement of A1 longitudinal-optical (LO) mode is found with 325nm laser excitation.For pseudomorphic samples,the frequencies of A1 (LO) phonons agree well with the theoretical predictions,which verifies that the samples are fully strained.For relaxed In_(x)Ga_(1-x)N samples,a linear dependence of the A1 (LO) mode frequency is obtained:Ωo(x) =(740.8 ± 3.3) - (143.1 ± 16.0)x,which is the evidence of one-mode behavior in In_(x)Ga_(1-x)N ternary alloys.Residual strains in these partially relaxed samples are also evaluated.

Influence of Dry Etching Damage on the Internal Quantum Efficiency of Nanorod InGaN/GaN Multiple Quantum Wells

The influence of dry etching damage on the internal quantum efficiency of InGaN/GaN nanorod multiple quantum wells (MQWs) is studied.The samples were etched by inductively coupled plasma (ICP) etching via a selfassembled nickel nanomask,and examined by room-temperature photoluminescence measurement.The key parameters in the etching process are rf power and ICP power.The internal quantum efficiency of nanorod MQWs shows a 5.6 times decrease substantially with the rf power increasing from 3W to 100W.However,it is slightly influenced by the ICP power,which shows 30% variation over a wide ICP power range between 30W and 600W.Under the optimized etching condition,the internal quantum efficiency of nanorod MQWs can be 40% that of the as-grown MQW sample,and the external quantum efficiency of nanorod MQWs can be about 4 times that of the as-grown one.

Enhanced Light Output of InGaN-Based Light Emitting Diodes with Roughed p-Type GaN Surface by Using Ni Nanoporous Template

Roughened surfaces of light-emitting diodes(LEDs)provide substantial improvement in light extraction efficiency.By preparing the self-assemble nanoporous Ni template through rapid annealing of a thin Ni film,followed by a low damage dry etching process,a p-side-up LED with a roughened surface has been fabricated.Compared to a conventional LED with plane surface,the light output of LEDs with nanoporous p-GaN surface increases up to 71%and 36%at applied currents of 1 mA and 20 mA,respectively.Meanwhile,the electrical characteristics are not degraded obviously after surface roughening.

Growth and Properties of Blue and Amber Complex Light Emitting InGaN/GaN Multi-Quantum Wells

Blue-red complex light emitting InGaN/GaN multi-quantum well(MQW)structures are fabricated by metal organic chemical vapor deposition(MOCVD).The structures are grown on a 2-inch diameter(0001)oriented(c−face)sapphire substrate,which consists of an approximately 2-µm−thick GaN template and a five-period layer consisting of a 4.9-nm-thick In0.18Ga0.82N well layer and a GaN barrier layer.The surface morphology of the MQW structures is observed by an atomic force microscope(AFM),which indicates the presence of islands of several tens of nanometers in height on the surface.The high resolution x−ray diffraction(XRD)θ/2θscan is carried out on the symmetric(0002)of the InGaN/GaN MQW structures.At least four order satellite peaks presented in the XRD spectrum indicate that the thickness and alloy compositions of the individual quantum wells are repeatable throughout the active region.Besides the 364 nm GaN band edge emission,two main emissions of blue and amber light from these MQWs are found,which possibly originate from the carrier recombinations in the InGaN/GaN QWs and InGaN quasi-quantum dots embedded in the QWs.

Gallium Nitride Nanowires Grown by Hydride Vapor Phase Epitaxy

GaN nanowires are grown by hydride vapor phase epitaxy using nickel as a catalyst.The properties of the obtained GaN nanowires are characterized by scanning and transmission electron microscopy,electron diffraction,roomtemperature photoluminescence and energy dispersive spectroscopy.The results show that the nanowires are wurtzite single crystals growing along the[0001]direction and a redshift in the photoluminescence is observed due to a superposition of several effects.The Raman spectra are close to those of the bulk GaN and the significantly broadening of those modes indicates the phonon confinement effects associated with the nanoscale dimensions of the system.

国产复方克霉唑乳膏体外透皮吸收研究

目的建立复方克霉唑乳膏体外透皮吸收测定方法,并以进口克霉唑乳膏作为参比,分析国产乳膏体外透皮差异情况。方法采用离体猪耳背皮肤作为透皮试验材料、30%乙醇-生理盐水为接收液,改良Franz扩散池法考察乳膏在32℃环境下透皮吸收规律,分别以LC-MS/MS法测定接收液中克霉唑吸收量随时间的变化、HPLC法测定试验结束后离体皮肤内克霉唑滞留量。结果3批国产乳膏与进口乳膏透皮量的比值分别为:1.32、1.75、1.62,皮内滞留量的比值分别为:1.19、1.57、1.32,4批乳膏皮内滞留量与透皮吸收总量的比例为88.03%~90.19%,皮内滞留量远高于透过量,符合该类药物临床用药特性,但国产制剂的平均粒径远高于进口制剂。结论国产复方制剂体外透皮性能均高于进口制剂,但不同企业制剂间存在差距,有待进一步优化;新建方法适用于复方克霉唑乳膏体外透皮吸收测定,可为半固体制剂质量评价提供依据,同时为其他复方制剂品种的研发和处方工艺优化提供借鉴。

往复筒法测定非洛地平缓释片体外释放度

目的:采用往复筒溶出度测定装置建立非洛地平缓释片的体外释放方法,比较参比制剂与仿制制剂的体外释放一致性。方法:分别以含0.3%聚山梨酯80(tween 80)、0.1%十六烷基三甲基溴化铵(hexadecyl trimethyl ammonium bromide,CTAB)、0.2%十二烷基硫酸钠(sodium dodecyl sulfate,SDS)的不同的pH缓冲液(第1排pH为1.2,第2排pH为6.5)为溶出介质,水浴温度为37℃,往复频率为10 dpm,采用往复筒装置测定参比制剂及仿制制剂的溶出曲线,并使用f2因子法评价其相似性。结果:与参比制剂相比,厂家A在3种介质均不相似,厂家B在含SDS的介质中不相似,厂家C在含聚山梨酯80和CTAB的介质中不相似。仿制制剂与参比制剂在体外溶出方面存在不同程度的差异。结论:本文建立的往复筒法模拟了胃肠道环境,其低水平的往复频率达到与桨法高转速相同的效果,在仿制药工艺改进方面具有一定参考价值。

替硝唑葡萄糖注射液杂质的色谱-质谱结构鉴定

本文采用UPLC-Q Exactive四极杆-静电场轨道阱高分辨液质联用技术,结合对照品保留时间定位、有机反应理论、紫外光谱等手段检测并鉴定了替硝唑葡萄糖注射液杂质谱中的5个杂质,分别为2-甲基-5-硝基咪唑(杂质1)、5-羟甲基糠醛(杂质2)、1-(2-乙基磺酰基-乙基)-2-甲基-4-硝基-1H-咪唑(杂质5)、1-[2-(乙硫氧基)乙基]-2-甲基-5-硝基-1H-咪唑(杂质6)和1,4-二-N-氧代-2-甲基-5-硝基-1H-咪唑(杂质8),其中杂质6和杂质8为首次报道。该研究为替硝唑葡萄糖注射液的工艺优化和质量控制提供了参考依据。

华佗救心丸GC-MS特征图谱及3个成分的含量测定

目的:利用气相色谱-质谱(gas chromatography-mass spectrometry,GC-MS)联用技术,建立华佗救心丸GC-MS特征图谱,同时测定龙脑、异龙脑和麝香酮3个成分的含量。方法:采用VF-WAXms毛细管色谱柱(0.25 mm×30 m,0.25μm),柱温为程序升温(140℃,停留2 min,然后以35℃·min^(-1)线性升温至230℃,停留5 min),进样口温度:210℃,检测器温度250℃;离子源为电子轰击源(electrospray ion source,EI),离子源温度为230℃,MS四极杆温度为150℃,发射电流为34.6μA,发射能量为70.0 eV,质谱监测模式为全扫描(SCAN),溶剂延迟为3 min。应用2012版中药色谱指纹图谱相似度评价软件对12批华佗救心丸进行相似度分析,同时对龙脑、异龙脑和麝香酮3个成分含量进行测定。结果:建立了华佗救心丸的GC-MS指纹图谱,12批华佗救心丸的色谱图与特征图谱的相似度均在0.999以上,标定共有峰8个,并指认了其中3个共有峰,分别为异龙脑、龙脑和麝香酮。12批样品中龙脑、异龙脑和麝香酮的含量范围分别为每丸0.8757~1.5250 g、0.7304~1.1405 g、0.0971~0.1120 g。结论:所建立的GC-MS特征图谱结合3个成分的含量测定,能较全面地反映华佗救心丸中挥发性化学成分质量,该方法简便可行,准确稳定,重复性和专属性好,可对华佗救心丸质量控制提供参考。

亚硫酸氢钠甲萘醌注射液中4个降解杂质的UPLC-Q-Orbitrap HRMS结构鉴定

目的:以超高效液相色谱-四极杆/静电场轨道阱质谱(UPLC-Q-Orbitrap HRMS)技术为主要手色谱段,结构定性亚硫酸氢钠甲萘醌注射液中的4个降解杂质。方法:超高效液相色谱采用Thermo Gold C_(18)色谱柱(100 mm×2.1 mm,1.9μm),以0.02 mol·L^(-1)乙酸铵溶液-甲醇(92∶8)为流动相,质谱采用HESI离子源、正负离子检测模式,碎片分析借助MsFrontier7.0软件,结构定性分析亚硫酸氢钠甲萘醌注射液中的4个降解杂质。结果:通过HPLC-PDA、UPLC-HRMS、^(1)HNMR等手段,结合有机合成制备杂质对照品、强制降解试验归属杂质来源、推测形成路径等方式,确定了亚硫酸氢钠甲萘醌的4个重要的降解杂质的分子结构,它们分别是:3-羟甲基-1,4-二-氧代-1,4-二-氢-2-萘磺酸钠(杂质1)、1-羟基-3-甲基-4-氧代-1,2,3,4-四-氢萘-1,3-二-磺酸钠(杂质2)、4-羟基3-甲基-1-氧代-1,2-二-氢-萘磺酸钠(杂质3)和1,4-二-羟基3-甲基-2-萘磺酸钠(杂质4)。结论:通过降解杂质结构定性及其互变异构、自氧化等机制研究,为亚硫酸氢钠甲萘醌注射液的工艺优化和质量控制提供了参考依据。