Efficient Quantum Dot Light-Emitting Diodes Based on Well-Type Thick-Shell CdxZn1−xS/CdSe/CdyZn1−yS Quantum Dots

Device grade quantum dots (QDs) require QDs ensembles to retain their original superior optical properties as in solution. QDs with thick shells are proven effective in suppressing the inter-dot interaction and preserving the emission properties for QDs solids. However, lattice strain–induced defects may form as the shell grows thicker, resulting in a notable photoluminescence quenching. Herein, a well-type Cd_xZn_1−xS/CdSe/Cd_yZn_1−yS QDs is proposed, where ternary alloys CdZnS are adopted to match the lattice parameter of intermediate CdSe by separately adjusting the x and y parameters. The resultant thick-shell Cd_0.5Zn_0.5S/CdSe/Cd_0.73Zn_0.27S QDs reveal nonblinking properties with a high PL QY of 99% in solution and 87% in film. The optimized quantum dot light-emitting diodes (QLEDs) exhibit a luminance of 31547.5 cd m⁻² at the external quantum efficiency maximum of 21.2% under a bias of 4.0 V. The shell thickness shows great impact on the degradation of the devices. The T₅₀ lifetime of the QLEDs with 11.2 nm QDs reaches 251 493 h, which is much higher than that of 6.5 and 8.4 nm QDs counterparts. The performances of the well-type thick-shell QLEDs are comparable to state-of-the-art devices, suggesting that this type of QDs is a promising candidate for efficient optoelectronic devices.     

基于粒子滤波的运动目标光电定位仿真研究

运动目标的光电定位不能像静止目标那样简单做均值滤波，鉴于此，引入粒子滤波算法，它不仅可以应用于线性系统，而且还适用于非线性系统。结合光电定位需求，详细推导了计算公式及初值和参数选取公式，对只含测量噪声以及含有测量和运动噪声等的海面运动目标光电无源定位算法进行了仿真计算，验证了算法的有效性，讨论了噪声强度对滤波效果的影响，滤波参数选择对滤波效果的影响，目标运动方式对滤波跟随性的影响，重采样算法对滤波效果的影响等。所得结论为:粒子滤波可用于运动目标光电定位过程，可有效降低定位误差；粒子滤波算法具有较强鲁棒性，适用于噪声较大、目标运动形态变化大等情况。     

交错群A_5与二面体群D_6直积的整群环的挠单位

本文利用Luthar-Passi方法,研究了五次交错群A_5与六阶二面体群D_6直积的整群环的挠单位,得到了该群的Zassenhaus猜想成立.     

PVDF-H1.6 Mn1.6 O4锂离子筛膜的制备及其提锂性能

锂元素是现代社会中重要的能源元素和战略资源,锂离子筛吸附法被认为是从盐湖卤水和海水中提锂最有前景的方法.然而,锂离子粉末具有流动性和渗透性较差的特点,制膜是一种典型的将之用于工业化的手段.本研究首先制备了多孔球型尖晶石型Li1.6 Mn1.6 O4,然后利用相转化法成功制得了PVDF-Li1.6 Mn1.6 O4多孔交联膜,酸浸后得到了PVDF-H1.6 Mn1.6 O4锂离子筛膜.吸附实验表明,当Li1.6 Mn1.6 O4负载量为11.9;时,其对应锂离子筛膜的Li+吸附容量最高,可以达到404 mg/m2,循环实验和选择性实验表明锂离子膜具有较好的循环利用性和Li+选择性.     

电化学法检测水果中抗坏血酸含量的本科生综合化学实验

将电化学检测方法引入到本科教学实验中，设计了利用循环伏安法检测水果中抗坏血酸含量的综合探究性实验。采用多壁碳纳米管为活性物质，通过红外光谱表征材料化学组成，通过透射电子显微镜表征材料形貌特征，利用抗坏血酸在电极表面的氧化反应，通过反应电流曲线定量测定水果中抗坏血酸的含量。该实验原料贴近生活，能够提高学生参与积极性，所涵盖电化学理论较系统，有助于学生灵活掌握课本上的电化学知识，涉及了部分科研类大型仪器设备，帮助学生学习和了解仪器使用方法及工作机理，提高学生钻研热情。该实验可作为化学化工类本科生专业综合性实验开设。     

含裂纹结构可靠度的多尺度求解

针对环境作用下金属结构从微观损伤到宏观失效的复杂过程,选用具有局部细化特征的CAS小波,先对疲劳裂纹扩展方程进行离散处理,将微分方程转化为代数方程组,然后用完全积分可靠性分析模型,对一般环境中和引入环境系数的含裂纹结构的可靠度进行求解.最后,验证了利用CAS小波多尺度方法求解复杂环境中结构疲劳破坏过程是可行的,并能很好地解决短裂纹与长裂纹扩展的光滑过渡.     

不同配副下ZrB2-SiC复相陶瓷的摩擦学性能

以微米级ZrB_2和SiC粉末为原料,采用热压烧结制备ZrB_2-SiC复相陶瓷,考察了SiC含量,摩擦对偶,速度和载荷对ZrB_2-SiC复相陶瓷摩擦磨损特性的影响.结果表明:ZrB_2-SiC复相陶瓷的摩擦系数和磨损率对SiC含量和摩擦对偶的变化较为敏感,速度和载荷变化,摩擦系数和磨损率的波动较大;以WC为对偶,速度0.1 m/s,载荷5 N时的ZrB_2-SiC复相陶瓷的平均摩擦系数和磨损率分别仅为0.4和2.41×10–4 mm3/(N·m).ZrB_2-SiC复相陶瓷的磨损机制以机械磨损为主,伴有轻微摩擦氧化,摩擦层的形成有利于摩擦系数的减小.     

液相色谱-同位素稀释串联质谱法测定动物源性食品中硝基呋喃类代谢物残留

加入同位素标记物的动物源性样品(龙虾、肠衣),在酸性条件下用2-硝基苯甲醛,使样品中呋喃唑酮、呋喃西林、呋喃它酮、呋喃妥因实现衍生。经乙酸乙酯提取浓缩、用甲醇水溶液溶解过滤后,滤液用液相色谱-串联质谱定量。在0.5,1.0和2.0μg/kg3个浓度水平上进行添加回收试验,回收率为80.1％～92.2％,检出限(LOQ)...     

Tuning of NaTaO_3 Band Structure through Mn~（2＋） Ion Doping and the Enhanced Visible Light Response

Pure and Mn-doped NaTaO3 nanoparticles were synthesized by a simple hydro- thermal method. XRD and XPS results suggested that manganese ions were successfully doped into the NaTaO3 crystalline in Mn2＋ state. UV-vis diffuse reflectance spectra revealed the obvious red-shift in the series of manganese doped NaTaO3 nanoparticles, resulting in a decrease in the band gap of NaTaO3 with the increase of Mn2＋ doping concentration. The photo-degradation experiment indicated that manganese doped NaTaO3 showed good photocatalytic performance and methylene blue（MB） degradation is improved with lower doping concentration of manganese ions under visible light. The simulation of energy band structure by density functional theory unfolded that the substitution of Ta5＋ ions by Mn2＋ ions resulted in an intermediate band（IB） below the bottom of the conduction band（CB）, which was mainly attributed to the state of Mn 3d.     

Possible Spectrums of 3×3 Upper Triangular Operator Matrices

Let H1, H2 and H3 be infinite dimensional separable complex Hilbert spaces. We denote by M(D,E,F) a 3×3 upper triangular operator matrix acting on H1⊕H2⊕H3 of the form M(D,E,F)=(A D E 0 B F 0 0 C). For given A ∈ B(H1), B ∈ B(H2) and C ∈ B(H3), the sets UD,E,F σp(M(D,E,F)), ∪D,E,F σr(M(D,E,F)), ∪D,E,F σc(M(D,E,F)) and ∪D,E,F σ(M(D,E,F)) are characterized, where D ∈ B(H2,H1), E ∈ B(H3, H1), F ∈ B(H3, H2) and σ(·), σp(·), σr(·),σc(·) denote the spectrum, the point spectrum, the residual spectrum and the continuous spectrum, respectively.