0.14 THz高分辨力成像雷达信号处理

为适应0.14 THz超高分辨雷达实时成像的需求,开发了基于CPU+GPU+FPGA的硬件架构和成像处理算法,算法以距离-多普勒为原型,引入L类维格纳分布变换提高横向分辨力,用Keystone变换方法对越距离单元徙动进行校正,并开发了系统非线性补偿算法。在载频0.14 THz、带宽5 GHz雷达样机上进行了逆合成孔径雷达成像试验,获得了3 cm3 cm的成像分辨力和实时成像能力,验证了信号处理方法的有效性。     

纳米La_(0.8)K_(0.2)FeO_3和La_(0.8)K_(0.2)Fe_(0.97)Pt_(0.03)O_3催化剂对柴油机NO_x和碳烟排放的影响

通过柠檬酸凝胶-浸渍法制备了具有介孔结构的纳米La_(0.8)K_(0.2)FeO_3和La_(0.8)K_(0.2)Fe_(0.97)Pt_(0.03)O_3催化剂,并利用XRD、SEM和BET对其性能进行表征。基于台架试验,研究了温度对纳米La_(0.8)K_(0.2)FeO_3和La_(0.8)K_(0.2)Fe_(0.97)Pt_(0.03)O_3催化剂同时脱除柴油机NO_x和碳烟排放的影响。结果表明,在温度150~350℃范围内,La_(0.8)K_(0.2)Fe_(0.97)Pt_(0.03)O_3作用下NO_x转化率较高;在温度350~400℃范围内,La_(0.8)K_(0.2)FeO_3作用下NO_x转化率较高,最高达27.5%。此外,在催化剂作用下副产物N_2O排放也得以降低。     

掺镁氧化铁电极光响应n-p型转换的研究

Electrodes were prepared with heating commercial pure iron chips buried in Mgo powder and showe dboth n-and p-type photoresponses.The photoresponses were so weak that in fact they were totally buried inthe noise.Hence asignal averager was used. After 1000 cycles'summation the signal to noise ratio was greatly improved and we obtained a wave form series showing the conversion of n-type, p-type photoresponses for the first time. Fig.1(a): E=0.261V. The absolute peak-to-peak photovoltagevalue (ΔV_(ph)) equals 13.4 mV and shows a typical n-type photoresponse. (b); E=-0.04 V, ΔV_(ph)=1.24 mV, still an -n-type response, but when light is chopped off, the electrode potential reaches its stable value much faster than in (a). (c): When E=-0.076 V, which is only 0.036 V more negative than in (b), in the latter 85% part of illuminating period, electrode potential tends to increase, demonstrating some p-type character. (d): As E=-0.09 V, the magnitude of p-type response almost equals that of n-type. (e): As E=-0.12 V, the main response belongs to p-type, and ΔV_(ph) is only 0.634 mV. This electrode potential is much more positive than the flat band potential of the undoped iron oxide electrode (E_(fb) is about -0.5 V). (f): E=-0.17 V. There is still a small n-type response at the beginning of every illuminating period, and the whole curve appears to be p-type responnse. (g): E=-0.36 V. Typical p-type response appears. ΔV_(ph)=2.05 mV. (h) and (i): E=-0.40 V and -0.45 V. ΔV_(ph) drop to 1.55 mV and 1.05 mV respectively. the above data were reproducible, no retardation of photoresponse was observed when potential was changed.An XPS surface analysis was performed thereafter on the same electrode. A peak of Mg1S at 1305 eV(BE) is apparent. Huge amount of Mg exists on the surface layer. the relative atomic concentration (s compared with Fe) reaches 15-20 AT%. After Ar~+ etching, the amount of Mg decreases. Fig.2 is the result after 9 minutes′ Ar~+ etching. A possible explanation of these experimental facts based on model of energy band of semiconductors was given.     

大流量PUF采样-气相色谱质谱联用测定广州市大气中多环芳烃

采用PS-1型大流量聚氨酯泡沫(PUF)大气采样器,采集了2004年夏季5、6、7三个月广州市区和郊区两个采样点20个大气样品,用气相色谱-质谱联用仪测定了其中16种多环芳烃的含量。结果表明,广州夏季市区和郊区大气中16种多环芳烃(气相和颗粒相)(∑16-PAHs)浓度范围分别为49.33~329.37ng/m3和30.11~97.97ng/m3,市区与郊区∑16-PAHs平均浓度分别为144.25ng/m3和58.79ng/m3,市区明显要高于郊区;市区和郊区苯并[a]芘(BaP)平均浓度分别为1.17ng/m3和0.76ng/m3,均未超过国家空气质量标准。     

气相色谱-质谱法同时测定粮谷及油籽中多种酰胺类除草剂残留量

粮谷及油籽样品经丙酮-水提取,经去脂和弗罗里硅土固相萃取小柱净化,气相色谱-质谱(GC-MS)选择离子监测模式(SIM)对净化液进行检测;一次进样,便可对粮谷及油籽样品中的9种酰胺类除草剂及常混用的莠去津和嗪草酮等除草剂残留进行准确定量和确证。除草剂回收率为63%~96%;相对标准偏差为2.1%~11.2%;定量下限为0.02~0.05 mg/kg。该法快速、灵敏、准确,各项技术指标均满足农药残留检测的要求。     

直流偏压对于在玻碳电极上双层类脂膜成膜过程的影响

应用循环伏安法和电化学阻抗谱研究了直流偏压对卵磷脂在玻碳电极表面自组装成膜过程及其结构的影响.实验发现:无论在正偏压还是负偏压条件下,卵磷脂在玻碳电极上均可组装成膜.施加正偏压时,由于玻碳电极表面所带的正电荷与卵磷脂端基之间的静电作用,使得卵磷脂在电极表面倾向于形成双层的类脂膜,并在0.4V偏压下电极阻抗达到最大值.继续增大电极正向偏压,s-BLM缺陷增加,以至趋于被击穿.提出了适宜的等效电路,并据此非线性拟合电极过程,求得部分阻抗的模型参数.研究发现:膜电容和电荷传递电阻呈现良好的互补效应.     

Synthesis, Structure, and Magnetic and Optical Properties of a Novel Chain-like Oxalate-bridging Samarium Complex

A new lanthanide complex [Sm(C2O4)(H2O)5]nCln·2nH2O has been obtained by hydrothermal synthetic method. The crystal belongs to monoclinic, space group P21/n, with a = 7.5438(6), b = 14.3201(11), c = 10.8608(9) , β = 94.565(4)o, V = 1169.55(16) 3, C2H14ClO11Sm, Mr = 399.93, Z = 4, Dc = 2.271 g/cm3, μ = 5.290 cm1, F(000) = 772, the final R = 0.0271 and wR = 0.0632 for 1880 observed reflections with I > 2σ(I). X-ray crystal analysis reveals that each Sm(III) atom is nine-coordinated by four oxygen atoms from two oxalate ligands and five coordinated water molecules in a distorted tricapped trigonal prism. The chain-like structure of lanthanide oxalate is reported for the first time. The fluorescent property and magnetic behavior of the title compound were investigated. The θ of –14.3(2)° and J of –0.26 cm-1 indicate antiferromagnetic interaction in the molecule.     

Synthesis and Structural Characterization of a Cyano-bridged 1-D Lanthanum(Ⅲ)-iron(Ⅲ) Complex [La(DMSO)_5(H_2O)](μ-CN)_2[Fe(CN)_4]·H_2O

A new lanthanumⅢ-ironⅢ complex [La(DMSO)5(H2O)](μ-CN)2[Fe(CN)4]·H2O 1 (DMSO=dimethylsulfoxide) has been prepared by a facile approach,ball-milling method,and characterized by X-ray diffraction. The crystal belongs to monoclinic,space group P21/n with a= 9.7125(3),b=21.5336(7),c=14.3804(5),β=93.242(3)o,C16H34FeLaN6O7S5,Mr=777.55,V =3002.8(2)3,Z=4,Dc=1.720 g/cm3,S=1.053,μ(MoKα)=2.278 mm–1,F(000)=1564,R= 0.0490 and wR=0.1270. The crystal structure analysis of 1 reveals a slightly distorted square-antiprism eightfold-coordinated La(Ⅲ) ion and a 1-D zigzag chain structure extending through the Fe-CN-La-NC-Fe linkages. The [La(DMSO)5(H2O)](μ-CN)2[Fe(CN)4] species are held together via hydrogen bonds to form a three-dimensional framework.     

石墨烯的制备、功能化及在化学中的应用

石墨烯是最近发现的一种具有二维平面结构的碳纳米材料, 它的特殊单原子层结构使其具有许多独特的物理化学性质. 有关石墨烯的基础和应用研究已成为当前的前沿和热点课题之一. 本文仅就目前石墨烯的制备方法、功能化方法以及在化学领域中的应用作一综述, 重点阐述石墨烯应用于化学修饰电极、化学电源、催化剂和药物载体以及气体传感器等方面的研究进展, 并对石墨烯在相关领域的应用前景作了展望.     

连续流动分析法测定电子烟烟液中的烟碱

称取电子烟烟液样品0.100 0g于25mL具盖离心管中,加入15%(体积分数)异丙醇溶液10mL,溶解混合,静置后作为样品溶液。如果在静置过程中出现不完全混溶现象,可将离心管置于涡旋振荡器内,以5 000转·min~(-1)的转速振荡1min,离心后,取澄清液体作为样品溶液。用连续流动分析仪测定样品溶液在波长460nm处的吸光度。烟碱的质量浓度在10.0～500mg·L~(-1)内与其对应的吸光度呈线性关系,测定下限(10s)为1.5mg·L~(-1)。方法用于测定市售电子烟烟液中的烟碱,测定值与标记值基本相符,加标回收率在99.5%～101%之间,测定值的相对标准偏差(n=6)为0.66%。