基于木材化学组分的银杏系统进化问题研究

采用傅里叶变换红外光谱(FTIR)法测定了银杏、苏铁、毛白杨等22个针阔树种木材的红外光谱,分析了指纹区内吸收峰数目差异以及纤维素、木质素两种物质的特征吸收峰位置和相对强度的变化规律,进而探讨了银杏的系统进化问题。结果表明：银杏的红外光谱与苏铁差异较大,与松杉类等针叶树种比较相似,说明银杏在木材的化学组成上较苏铁更为进化,与松杉类等针叶树有较近的亲缘关系;银杏木材木质素的含量较一般针叶树高,这可能是一种遗留下来的古老性状;银杏木材中含有较多的紫丁香基木质素,表明银杏有向阔叶树进化的趋势。     

超声波法提取啤酒花中总多糖的工艺

采用超声波法提取啤酒花中总多糖.采用正交试验设计,以总多糖含量为评价指标进行实验.最佳提取工艺为:超声提取2次,加12倍量的水,每次40min,超声功率为160W.本提取工艺合理,啤酒花中总多糖提取率较高.     

Characterization of different-Al-content AlGaN/GaN heterostructures on sapphire

Al x Ga 1-x N/GaN high-electron-mobility transistor (HEMT) structures with Al composition ranging from x = 0.13 to 0.36 are grown on sapphire substrates by low-pressure metalorganic chemical vapor deposition (LP-MOCVD). The effects of Al content on crystal quality, surface morphology, optical and electrical characteristics of the AlGaN/GaN heterostructures have been analyzed. Although high Al-content (36%) heterostructure exhibits a distinguished photoluminescence peak related to recombination between the two-dimensional electron gas and photoexcited holes (2DEG-h), its crystal quality and rough surface morphology are poor. 2DEG mobility increases with the Al content up to 26% and then it apparently decreases for high Al-content (36%) AlGaN/GaN heterostructure. The increase of sheet carrier density with the increase of Al content has been observed. A high mobility at room temperature of 2105 cm 2 /V s with a sheet carrier density of n s = 1.10 × 10 13 cm -2 , for a 26% Al-content AlGaN/GaN heterostructure has been obtained, which is approaching state-of-the-art for HEMT grown on SiC. Sheet resistance as low as 274 Ω/□ has also been achieved.     

用近红外无损肌氧及运动心率检测技术评定100 m极量强度运动对心脏冲击影响

利用连续双波长近红外光技术测量肌肉中血红蛋白含氧量的变化情况,同时应用运动心率无线实时采集设备,设计了检测实时肌肉组织血氧含量和瞬时心率实验方案,对6名健康男性进行了100 m跑同步实测实验。实验表明,肌肉组织氧合血红蛋白浓度在100 m跑结束后继续降低,达到最低值的时刻滞后于运动结束时刻的时间为(6.65±1.10)s;心率则在运动结束后继续上升,达到最高值的时刻滞后于运动结束时刻的时间为(8.00±1.57)s。这些结果显示了双波长近红外光组织氧测试技术和运动心率无线实时采集系统能够正确检测极量强度运动时的血氧参数和心率,揭示了极量强度运动过程中肌肉中氧运输与消耗的过程及其与心率之间的动力学特征。     

Generation and Quantum Interference of Entangled Electron-Hole Pairs in a Hanbury Brown and Twiss Interferometer

The Hanbury Brown-Twiss interferometer is proposed to serve as a detector of the crossed Andreev reflection and to generate entangled electron-hole pairs. It is shown that the non-local electron and hole induced by the crossed Andreev reflection are entangled. Quantum interference of the entangled electron-hole pairs gives rise to a new measurable effect of the phase difference between two superconductors in the cross correlation. The present theoretical predictions can be experimentally realized within the present-day microelectronic technology.     

Analytical solution of a multidimensional Langevin equation at high friction limits and probability passing over a two-dimensional saddle

The analytical solution of a multidimensional Langevin equation at the overdamping limit is obtained and the probability of particles passing over a two-dimensional saddle point is discussed. These results may break a path for studying further the fusion in superheavy elements synthesis.     

缺陷对二维四方光子晶体透射光谱的影响

利用转移矩阵法研究了二维四方光子晶体中缺陷对透射光谱的影响。结果表明缺陷对TE波的影响比对TM波的影响明显,缺陷层填充比对禁带宽度影响很大,TE波禁带在填充比r/a=0.33时最宽,第一禁带的最低频率随着填充比的增加向低频移动。     

基于超声红外技术对金属管内壁缺陷的检测

为提高管道的运送效率,及时检测排除管道内壁的缺陷非常重要。提出利用超声红外无损检测方法对管道内部进行检测。超声主动热激励试件,高频红外热像仪记录试件表面温度变化,结合了超声摩擦生热和红外热成像的优点。对壁厚约为3.3mm检测难度较大的金属管内壁缺陷进行了检测。通过对采集数据和热图的处理分析,准确快速地确定缺陷所在的位置。实物对比分析表明：超声热激励红外无损检测技术可以对金属管道内壁缺陷进行准确检测定位。     

工矿业城市区域水质参数高光谱定量反演

工矿业城市区域易受工业活动、矿产开采影响,使其水环境遭受不同程度的破坏,以至于水体污染问题突出。当前常规水质监测主要采用“以点代面”的工作方式进行野外采样及其室内化验分析,然而环境复杂多变,空间差异大,导致调查点代表性受限,整体精度不高,效率低下,更难以实现区域性动态监测。以因矿兴市的矿业重镇湖北黄石大冶市为研究区,同步开展无人机高光谱航飞、地面光谱测量和水体样品采集测试,分别获得具有49个波段的高光谱影像数据和光谱分辨率为1 nm的水体光谱曲线,其中影像数据波谱范围为505~890 nm,光谱分辨率为7.78 nm,空间分辨率为30 cm。对获取的高光谱影像和光谱数据剔除异常值、光谱定标、辐射校正等预处理后,对比分析研究区内水体的不同光谱吸收、反射及光谱曲线形态特征信息,从而提取出高光谱影像和测量光谱的反射光谱曲线形态特征、去包络线后光谱曲线形态特征、三阶求导后光谱曲线形态特征和光谱四值编码共四大类25个光谱特征。采用皮尔森相关系数分析样品水质参数与光谱特征之间的相关性,以此筛选出存在显著相关的水质参数与光谱特征。在此基础上,采用逐步回归分析方法筛选出最大反射率及其波长位置、对称度、光谱编码Ⅲ、三阶导最大及最小值等光谱特征作为模型变量,构建出水质参数的多元线性反演模型,并对模型进行F检验和t检验。将检验后的反演模型推广运用于研究区内高光谱影像,获得尾矿库、河流、湖泊等典型区域的水质参数反演结果,从而实现“由点到面”水质参数信息的快速获取。结果显示水质参数pH、硬度（Ca2++Mg2+）、钾与氯离子比值（K+/Cl-）、镁与碱度比值[Mg2+/(HCO3-+CO2-₃)]的反演精度较高,其pH的判定系数R2最小为0.669,镁与碱度比值的判定系数R2最大为0.895,相对均方根误差均小于28%;而总溶解固体（TDS）反演精度较低,其判定系数R2仅为0.463,相对均方根误差达36.762%。提出了一种基于光谱曲线形态特征的高光谱遥感水质参数定量反演模型方法,实现了pH值、硬度、镁离子与碱度之比等水质参数的高光谱定量反演,为区域水环境动态监测提供了新方法。     

Heteronuclear Multiple-Quantum Coherence NMR Spectroscopy of Im-cyt C

Some ¹³C chemical shifts of the CH_n groups in the aliphatic side chains of Im-cyt c have been determined for the first time based on the H chemical shifts of their attached protons with the aid of heteronuclear multiple-quantum coherence (HMQC) spectroscopy. Comparison of chemical shifts of these specifically assigned ¹³C and H resonances from Im-cyt c with those from cyt c indicates that ¹³C-NMR spectra may provide an opportunity to probe the electronic structure and conformational changes induced by axial ligand substitution.