铜锡合金纳米粒子的制备和性能研究

通过化学还原方法制备了铜锡合金纳米粒子,并研究分析了其的尺寸和热学性能。铜锡纳米粒子的X射线衍射分析结果显示,合成产物主要是锡纳米颗粒和铜锡合金(Cu6Sn5)纳米颗粒组成,且这些纳米粒子并未被氧化。其示差扫描量热法测得结果表明,本次合成的纳米颗粒的熔点为202.98 ℃,适合现代电子封装技术对低熔点封装材料的要求。     

微结构低重叠度大范围三维拼接方法

针对微结构大范围无损测试问题,提出了一种低 重叠度的三维结构拼接方法。首先基于实验参数将结构特征提 取区域限制在测量过程中的重叠区域,以减少误匹配出现的可能性并提高计算效率;在上述 区域内,通过SIFT(scale-invariant feature transform)算法进行特征 点提取;在特征点匹配阶段,根据测量系统参数进一步提出缩小匹配点对搜索范围的方法以 提高特征点匹配可靠性;最后以 重叠区域的局部连续性为依据,计算校正矩阵以校正测量过程中环境扰动带来的拼接结构错 动。实验中,将本方法与目前商业设 备的拼接测量功能进行了对比。实验表明,本文方法不但适用于特征丰富的结构,也适用于 相似度高的阵列性结构,可在重叠度为6%时实现有效拼接。     

行波扰动对天波雷达慢速目标检测影响研究

利用电离层行波扰动(Traveling Ionospheric Disturbances,TIDs)模型,仿真分析了不同尺度TIDs引起的超视距雷达(Over the Horizon Radar,OTHR)地海杂波频谱频移、展宽以及对舰船目标检测的影响.结果表明:小尺度TIDs引起的附加多普勒频移幅度较小,但随时间变化较快,S形曲线扭曲较为严重,对OTHR影响主要表现为多普勒频移;中尺度和大尺度TIDs引起的附加多普勒频移相对于小尺度TIDs的有所增加,但随时间变化减缓,S形曲线扭曲程度减小,除引起地海杂波多普勒频移外,同时引起杂波频谱展宽,影响舰船目标检测.同时,还给出了不同尺度TIDs引起的海杂波频移、展宽抑制方法,经仿真验证,上述算法有效.     

超宽带低温接收机后级低噪声放大器设计

设计了一种用于超宽频低温接收机后级放大的宽带低噪声放大器,并给出了仿真和测试结果。该低噪声放大器采用三个单片级联,并在级间加入了均衡和衰减网络对增益进行修正,使增益平坦度得到很大改善,同时对噪声等指标影响较小。最终实现的低噪声放大器在1～9GHz 频率范围内,常温噪声系数优于2dB,增益大于35dB,平坦度小于3.5dB,输入输出驻波比小于2.5,输出1dB 压缩点功率大于10dBm。     

高速相干光通信系统中水印辅助的低密度奇偶校验方案

为了研究水印辅助的低密度奇偶校验(LDPC)方 案在高速相干接收光通信系统 中的译码性能,提出了一种适用于相干光通信系统的水印符号辅助的LDPC前向纠错方案 ,与传统LDPC相比,可以大大提高相干接 收机的抗噪声能力。在100Gbit/s 16进制正 交幅度高制(16QAM)相干接收光通信系统上的仿真实验结果表明, 在误码率(BER)为10－9时, 所提出的前向纠错方案与传统LDPC相比 较,信噪比(SNR)增益提高了0.45dB ;同时,在相同BER下,水印符号辅助的LDPC方 案的译码迭代次数有很明显的降低。     

单通道副瓣影响分析及抑制方法

为了抑制天线副瓣对单通道目标检测的影响,文中通过比较实测天线方向图和回波方向图的特点,提出了利用搜索目标幅度最大值和方位向滑帧统计波束宽度的方法来抑制副瓣干扰,并通过仿真分析验证了算法的有效性。     

Detection of layer‐by‐layer self‐assembly multilayer films by low‐temperature plasma mass spectrometry

The detection of layer‐by‐layer self‐assembly multilayer films was carried out using low‐temperature plasma (LTP) mass spectrometry (MS) under ambient conditions. These multilayer films have been prepared on quartz plates through the alternate assembling of oppositely charged 4‐aminothiophenol (4‐ATP) capped Au particles and thioglycolic acid (TGA) capped Ag particles. An LTP probe was used for direct desorption and ionization of chemical components on the films. Without the complicated sample preparation, the structure information of 4‐ATP and TGA on films was studied by LTP‐MS. Characteristic ions of 4‐ATP (M) and TGA (F), including [M]^+?, [M‐NH₂]⁺, [M‐HCN‐H]⁺, and [F + H]⁺, [F‐H]⁺, [F‐OH]⁺, [F‐COOH]⁺ were recorded by LTP‐MS on the films. However, [M‐CS‐H]⁺ and [F‐SH]⁺ could not be observed on the film, which were detected in the neat sample. In addition, the semi‐quantitative analysis of chemical components on monolayer film was carried out, and the amounts of 4‐ATP and TGA on monolayer surface were 45 ng/mm² and 54 ng/mm², respectively. This resulted the ionization efficiencies of 72% for 4‐ATP and 54% for TGA. In order to evaluate the reliability of present LTP‐MS, the correlations between this approach and some traditional methods, such as UV–vis spectroscopy, atomic force microscope and X‐ray photoelectron spectroscopy were studied, which resulted the correlation coefficients of higher than 0.9776. The results indicated that this technique can be used for analyzing the films without any pretreatment, which possesses great potential in the studies of self‐assembly multilayer films. Copyright © 2013 John Wiley & Sons, Ltd.     

重度原油注空气低温氧化过程研究(英文)

低温氧化反应对现场燃烧(ISC)技术点火的成功有十分重要的影响.采用高压氧化管,研究了不同温度压力下,新疆克拉玛依重度原油的低温氧化过程.结果表明,温度和压力的变化对低温氧化反应的放热程度、持续时间以及气体产物有明显影响.适合油样低温氧化反应的温度和压力分别为150℃和10MPa.此外,采用纯组分替代原油族组分进行低温氧化实验,研究低温氧化反应对原油族组分(饱和烃、芳香烃、胶质、沥青质)含量的影响.结果表明,原油所含族组分中,芳香烃组分最易被氧化,其含量由氧化前的19.17%减少到12.38%(150℃)和9.51%(250℃).随着低温氧化过程的进行,结构复杂的族组分(胶质、沥青质)的含量明显增加.实验数据对油藏实施注空气技术,以及该技术现场实施条件的确定有十分重要的指导意义.     

Synthesis,isolation and characterization of methyl levulinate from cellulose catalyzed by extremely low concentration acid

A direct synthesis of methyl levulinate from cellulose alcoholysis in methanol medium under mild condition (180–210 °C) catalyzed by extremely low concentration sulfuric acid (≤0.01 mol/L) and the product isolation were developed in this study. Effects of different process variables towards the catalytic performance were performed as a function of reaction time. The results indicated that sulfuric acid concentration, temperature and initial cellulose concentration had significant effects on the synthesis of methyl levulinate. An optimized yield of around 50% was achieved at 210 °C for 120 min with sulfuric acid concentration of 0.01 mol/L and initial cellulose concentration below 100 g/L. The resulting product mixture was isolated by a distillation technique that combines an atmospheric distillation with a vacuum distillation where n-dodecane was added to help distill the heavy fraction. The light fraction including mainly methanol could be reused as the reaction medium without any substantial change in the yield of methyl levulinate. The chemical composition and structural of lower heavy fraction were characterized by GC/MS, FTIR, ¹H-NMR and ¹³C-NMR techniques. Methyl levulinate was found to be a major ingredient of lower heavy fraction with the content over 96%. This pathway is efficient, environmentally benign and economical for the production of pure levulinate esters from cellulose.     

High sensitivity chemiluminescence enzyme immunoassay for detecting staphylococcal enterotoxin A in multi-matrices

In this study, detection of staphylococcal enterotoxin A (SEA) in multi-matrices using a highly sensitive and specific microplate chemiluminescence enzyme immunoassay (CLEIA) has been established. A pair of monoclonal antibodies (mAbs) was selected from 37 anti-SEA mAbs by pairwise analysis, and the experimental conditions of the CLEIA were optimized. This CLEIA exhibited high performance with a wide dynamic range from 6.4 pg mL⁻¹ to 1600 pg mL⁻¹, and the measured low limit of detection (LOD) was 3.2 pg mL⁻¹. No cross-reactivity was observed when this method was applied to test SEB, SEC1, and SED. It has also been successfully applied for analyzing SEA in a variety of environmental, biological, and clinical matrices, such as sewage, tap water, river water, roast beef, peanut butter, cured ham, 10% nonfat dry milk, milk, orange juice, human urine, and serum. Thus, the highly sensitive and SEA-specific CLEIA should make it attractive for quantifying SEA in public health and diagnosis in near future.