一类双调和方程的多解性

本文研究了非线性项在无穷远处次线性增长的一类双调和方程解的存在性和多解性.应用抽象临界点定理,证明了此类双调和方程至少有三个弱解存在.     

内/外部励磁方式下高温超导环的俘获场特性

高温超导磁体在闭环运行时,可以提供稳定磁场,但是由于高温超导带材无法实现无阻焊接,成为高温超导磁体闭环运行的技术瓶颈.本文利用第二代高温超导带材制备闭环超导环,采用内部励磁和外部励磁对超导环进行励磁,在液氮温度中(77 K)测量超导环的中心俘获磁场.结果表明超导环在内部励磁俘获的磁场值比外部励磁俘获的磁场值高;外部励磁中,超导环中插入铁芯柱能提高俘获场;内部励磁中,超导环在螺线管闭环运行俘获的磁场值比开环运行俘获的磁场值高.结果对于高温超导闭环磁体励磁和高温超导带材磁通动力学研究具有很重要参考价值.     

Atomically Dispersed Ruthenium Species Inside Metal–Organic Frameworks: Combining the High Activity of Atomic Sites and the Molecular Sieving Effect of MOFs

Incorporating atomically dispersed metal species into functionalized metal–organic frameworks (MOFs) can integrate their respective merits for catalysis. A cage‐controlled encapsulation and reduction strategy is used to fabricate single Ru atoms and triatomic Ru₃ clusters anchored on ZIF‐8 (Ru₁@ZIF‐8, Ru₃@ZIF‐8). The highly efficient and selective catalysis for semi‐hydrogenation of alkyne is observed. The excellent activity derives from high atom‐efficiency of atomically dispersed Ru active sites and hydrogen enrichment by the ZIF‐8 shell. Meanwhile, ZIF‐8 shell serves as a novel molecular sieve for olefins to achieve absolute regioselectivity of catalyzing terminal alkynes but not internal alkynes. Moreover, the size‐dependent performance between Ru₃@ZIF‐8 and Ru₁@ZIF‐8 is detected in experiment and understood by quantum‐chemical calculations, demonstrating a new and promising approach to optimize catalysts by controlling the number of atoms.     

基于自适应遗传算法的质子调强放疗扫描路径优化

研究和开发了基于自适应遗传算法的质子调强放疗扫描路径优化方法,并在此基础上对质子调强放疗扫描时间进行初步临床评估。利用自适应遗传算法具有的较强容错性和全空间最优搜索能力开发点扫描质子调强路径优化模块,并将其集成到自主研发的放疗计划系统,选取AAPM TG-119头颈部肿瘤和前列腺肿瘤模拟例题及两例临床病例进行测试,对比扫描路径优化前后质子放疗计划扫描路径长度。对于AAPMTG-119头颈部肿瘤和前列腺肿瘤模拟例题,总扫描路径长度分别降低了27.17%和18.72%,临床头颈部肿瘤和前列腺肿瘤病例总扫描路径长度分别降低了25.36%和32.95%,优化前后路径长度降低比率与零权重扫描点及肿瘤解剖结构有关。基于自适应遗传算法的扫描路径优化方法可减少质子调强放疗计划扫描时间,从而缩短病人治疗时间,可广泛应用于质子重扫描临床技术。The objective of this research is to study and develop a proton spot scanning path optimization method using an improved genetic algorithm for proton therapy and to evaluate the scanning time under clinical conditions. An Improved Adaptive Genetic Algorithm (IAGA) based scanning path optimization module was developed and integrated into the home-grown treatment planning system. Four cases, including two AAPM TG-119 standard cases and two clinical cases, were selected to compare their scanning path length before and after scanning path optimization. For the two AAPM TG-119 cases, the optimized scanning path length dropped by 27.17% and 18.72%, and for the corresponding clinical cases, the optimized scanning path length dropped by 25.36% and 32.95% respectively. The performance of scanning path optimization was affected by the number of zero-weight spots and connected regions in the scanning map. IAGA based scanning path optimization can reduce the total scanning path length in intensity modulated proton therapy and, therefore, can be used in spot rescanning to accommodate organ motion.     

液相色谱-毛细管气相色谱/质谱离线联用分析烟草中的挥发性及半挥发性成分

建立了一种用于烟草样品中挥发性、半挥发性成分分析的液相色谱-毛细管气相色谱/质谱(LC-CGC/MS)离线联用方法。研究了LC-CGC/MS的分离机理。LC分析选用氨基分析柱(250 mm×2.0 mm, 5 μm)作为分析柱,正己烷-二氯甲烷-乙腈(90:6.6:3.4, v/v/v)作为流动相,对挥发性、半挥发性成分进行分离,收集得到5个馏分,并存放在5个氮吹瓶中。多次进样并收集相同时间段的馏分,氮吹浓缩至1 mL,然后分别进行CGC/MS分析,所用的CGC柱为DB-5MS(60 m×0.25 mm×0.25 μm)。结果显示,与直接采用CGC/MS分析相比,采用LC-CGC/MS分析复杂样本的效果更好,定性的可靠性更高。     

CO2激光偏频锁定技术的研究

本文对于CO_2激光外差接收单元技术之一的CO_2激光偏频锁定技术进行了研究,实现了两个自由振荡的CO_2激光器之间的差频的锁定,当采取一定措施尽量减小环境的影响后,得到了≤1 kHz(τ=10s)的频率跟踪精度,中心频率在2 MHz～20 MHz内连续可调.     

CO2激光外差探测系统灵敏度的研究

本文通过讨论探测器的信噪比和噪声等效功率的影响因素,研究了CO_2激光外差探测系统的灵敏度.     

A novel and effective Ni complex catalyst system for the coupling reactions of carbon dioxide and epoxides

The coupling of carbon dioxide and mono-substituted terminal epoxides or cyclohexene oxide to form cyclic carbonates under a Ni complex catalyst system without using additional organic solvents was achieved in excellent selectivity and TOF.     

732强酸性阳离子树脂催化合成盐酸维生素B1

以硫羟硫胺为原料,经双氧水氧化得硫酸维生素B1(VB1·H2SO4);VB1·H2SO4经纯化水稀释后,流经732强酸型阳离子交换树脂,用稀盐酸洗脱,浓缩后用85%乙醇重结晶得盐酸VB1,其结构经1H NMR,13C NMR,MS和元素分析确证。     

固态源MBE系统生长高质量的调制掺杂GaAs结构材料和InP/InP外延材料的兼容性研究

通过固态源的分子束外延系统生长了调制掺杂AlGaAs/GaAs结构材料和InP/InP外延材料.在生长含磷材料之后,生长条件(真空状态)变差;我们通过采取合理的工艺方法和生长工艺条件的优化,获得了电子迁移率为1.86×105cm2/Vs(77K)调制掺杂AlGaAs/GaAs结构材料和电子迁移率为2.09×105cm2/Vs(77K)δ-Si掺杂AlGaAs/GaAs结构材料.InP/InP材料的电子迁移率为4.57×104 cm2/Vs(77K),该数值是目前国际报道最高迁移率值和最低的电子浓度的InP外延材料.成功地实现了在一个固态源分子束外延设备交替生长高质量的调制掺杂AlGaAs/GaAs结构材料和含磷材料.