改进特征波段选取和混合集成建模的东北粳稻叶绿素含量估算

利用光谱信息快速、无损和准确的检测水稻冠层叶片叶绿素含量,对水稻的长势评估、精准施肥、科学管理都具有非常重要的现实意义。以东北粳稻为研究对象,以小区试验为基础,获取关键生长期的水稻冠层高光谱数据。首先采用标准正态变量校正法（SNV）对光谱数据进行预处理,针对处理后光谱数据,以随机蛙跳（RF）算法为基础,结合相关系数分析法（CC）和续投影算法（SPA）,提出一种融合两种初选波段的改进型随机蛙跳算法（fpb-RF）筛选叶绿素含量的特征波段,并分别与标准RF,CC 和SPA方法进行对比。以提取的特征波段作为输入,结合线性模型和非线性模型各自优势,提出一种高斯过程回归（GPR）补偿偏最小二乘（PLSR）的叶绿素含量混合预测模型（GPR-P）：利用PLSR法对水稻叶绿素含量初步预测,得到叶绿素含量的线性趋势,然后利用具有较好非线性逼近能力的GPR对PLSR模型偏差进行预测,两者叠加得到最终预测值。为了验证所提方法优越性,以不同方法提取的特征波段作为输入,分别建立PLSR、最小二乘支持向量机（LSSVM）、BP神经网络预测模型。结果表明：相同预测模型条件下,改进fpb-RF算法提取特征波段作为输入可较好的降低模型复杂性、提高模型预测性能,各模型测试集的决定系数（R2_P）和训练集的决定系数（R2_C）均高于0.704 7。另外,在各算法提取特征波段进行建模时,GPR-P模型的R2_C和R2_P均高于0.755 3,其中,采用fpb-RF方法提取的特征波段作为输入建立的GPR-P模型预测精度最高,R2_C和R2_P分别为 0.781 5和0.779 6,RMSEC和RMSEP分别为0.904 1和0.928 3 mg·L-1,可为东北粳稻叶绿素含量的检测与评估提供有价值的参考和借鉴作用。     

气相色谱-质谱法测定东北小鲵体内组织中的脂肪酸

用石油醚作溶剂在索氏提取器中分别提取东北小鲵体内组织(皮、肌肉及内脏)中的粗脂肪油,所得萃取液分别用饱和氯化钠溶液及纯水洗涤后加入无水硫酸钠脱水过夜.用旋转蒸发除去萃取液中有机溶剂,于是获得3份油状液体分别为从小鲵的皮、肌肉及内脏提取的脂肪酸.从中分取0.20 mL于氢氧化钾溶液中加甲醇做甲酯化处理,用乙醚-正己烷(2...     

Effect of sample preparation on the thermal degradation of metal-added biomass

The present study investigates the effect of different sample preparation methods on the pyrolysis behaviour of metal-added biomass; Willow samples were compared in the presence of two salts of zinc and lead containing sulphate and nitrate anions which were added to the wood samples with three different techniques as dry-mixing, impregnation and ion-exchange. The effect of acid and water wash as common demineralisation pre-treatments were also analysed to evaluate their roles in the thermal degradation of the biomass. Results from thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR) and pyrolysis-mass spectrometry (Py-MS) measurements indicated that these pre-treatments change the matrix and the physical–chemical properties of wood. Results suggested that these structural changes increase the thermal stability of cellulose during pyrolysis. Sample preparation was also found to be a crucial factor during pyrolysis; different anions of metal salts changed the weight loss rate curves of wood material, which indicates changes in the primary degradation process of the biomass. Results also showed that dry-mixing, impregnation or ion-exchange influence the thermal behaviour of wood in different ways when a chosen metal salt was and added to the wood material.     

Sonocatalytic damage of solute bovine serum albumin by disperse ZnO/porcine dens composite under ultrasonic irradiation

ZnO/Dens composite were prepared with nano-sized ZnO and porcine dens powders by mechanical mixing, liquid boiling, ultrasonic dispersion and heat-treated at 500°C for 50 min. The samples were characterized by X-ray diffraction (XRD) and its sonocatalytic activity was evaluated by the damage of bovine serum albumin (BSA). Furthermore, the effects of ultrasonic irradiation time, ZnO/Dens composite amount, solution acidity and ionic strength on the sonocatalytic damage of BSA were evaluated. The results show that the damage degree of BSA aggravated with the increase of ultrasonic irradiation time, ZnO/Dens composite amount and ionic strength, but weakened with the increase of solution acidity. In addition, the damage site to BSA molecules was analyzed by synchronous fluorescence spectra and the results exhibited that the damage site was mainly at tryptophan (Trp) residue. This study should be helpful to drive sonocatalytic method to treat tumors in clinic application.     

醚型菊酯类农药通用抗原的合成及鉴定

以2-(4-乙氧基苯基)-2-甲基丙醇和氯乙酸钠为原料,合成了醚型菊酯类农药通用半抗原Hapten I,经1 H-NMR及13C-NMR鉴定后,分别与牛血清蛋白(BSA)和卵清白蛋白(OVA)偶联,制得免疫原和包被原,经紫外光谱分析法计算得其偶联比分别为14∶1和35∶1,说明人工抗原合成成功.免疫Balb/c小鼠制备多克隆抗体,效价达1.28×105,用半抗原经间接竞争ELISA检测人工抗原的免疫原性,IC50和IC10值分别为0.2653和0.0012 mg/L,证明人工抗原具有较好的免疫原性.交叉反应表明此多克隆抗体具有良好的特异性.     

Wada bifurcations and partially Wada basin boundaries in a two-dimensional cubic map

The partially Wada basin boundaries are referred to the coexistence of Wada points and non-Wada points in the same basin boundary. We demonstrate two types of Wada bifurcations and analyze the transitions from totally Wada basins to partially Wada basins and from totally Wada basins to totally Wada basins in a two-dimensional cubic map. We describe some numerical experiments giving the evidence of partially Wada basin boundaries. Our results show that the basin cell erosion and the basin cell bifurcation can induce the Wada basin boundary metamorphoses.     

几种真菌多糖硫酸酯化修饰前后理化性质的比较研究

制备了平菇等5种真菌类硫酸酯化多糖,离子色谱法测得其含硫量为12%～15%,取代度为1.02～1.46.对其硫酸酯化修饰前后的柱层析行为、电泳行为、红外光谱、圆二色谱、比旋光度、特性黏度进行了系统的比较研究.结果表明,引入硫酸基后,多糖的相对分子质量增大,电泳迁移率增加,红外光谱和圆二色谱出现特征吸收峰,比旋光度发生显著变化,特性黏度明显降低,表明硫酸酯化修饰后多糖的构象发生了显著变化,可能形成了特定的部分有序结构.     

Synthesis and crystal structure of a terephthalato-bridged copper(II) complex [Cu2(tpt)(bpy)2(H2O)4] [Cu2(tpt)3 (bpy)2(H2O)2]

A terephthalato-bridged copper(II) complex [Cu₂(tpt)(bpy)₂(H₂O)₄][Cu₂(tpt)₃(bpy)₂ (H₂O)₂] (1) (tpt = terephthalate, bpy =; 2,2'-bipyridine) was synthesized by the reaction of Cu(ClO₄)₂ 6H₂O and terephthalic acid in the presence of 2,2'-bipyridine in H₂O solution. Crystal structure of 1 was determined by X-ray diffraction analysis in the triclinic space group P , with a = 10.7327(10) Å, b = 11.1658(11) Å, c = 17.3768(16) Å, = 108.063(2), = 91.064(2), = 116.721(2), V = 1737.5(3) ų, and Z = 2. Both the anion and the countercation in 1 are copper(II) complexes linked by terephthalate bridges in the bis(monodentate) (syn–anti) mode. The anion and the countercation are also linked by two hydrogen bonds between coordinating water molecules and terephthalate ligand.     

Polyoxometalate and Resin‐Derived P‐Doped Mo2C@N‐Doped Carbon as a Highly Efficient Hydrogen‐Evolution Reaction Catalyst at All pH Values

A new type of P‐doped Mo₂C coated by N‐doped carbon (P‐Mo₂C@NC) has been successfully prepared by calcining a mixture of H₃[PMo₁₂O₄₀] polyoxometalates (POMs) and urea‐formaldehyde resin under an N₂ atmosphere. Urea‐formaldehyde resin not only serves as the carbon source to ensure carbonization but also facilitates the uniform distribution of POM precursors, which efficiently avoid the aggregation of Mo₂C particles at high temperatures. TEM analysis revealed that the average diameter of the Mo₂C particles was about 10 nm, which is coated by a few‐layer N‐doped carbon sheet. The as‐prepared P‐Mo₂C@NC displayed excellent hydrogen‐evolution reaction (HER) performance and long‐term stability in all pH environments. To reach a current density of 10 mA cm^?2, only 109, 159, and 83 mV were needed for P‐Mo₂C@NC in 0.5 m H₂SO₄ (pH 0), 0.1 m phosphate buffer (pH 7), and 1 m KOH (pH 14), respectively. This could provide a high‐yield and low‐cost method to prepare uniform nanosized molybdenum carbides with highly efficient and stable HER performance.     

超声波-微分脉冲伏安法测定超痕量铜

以循环伏安和微分脉冲伏安法研究了超声作用下铜在铂电极上的电沉积行为,建立了超痕量铜的超声波-微分脉冲伏安法。超声波增加了铜的阳极溶出峰电流近一个数量级,提高了方法的灵敏度。在优化实验条件下,铜的微分脉冲阳极溶出峰电流与铜离子浓度在两个范围内呈线性关系。在5.00~200nmol/L的浓度范围内,线性方程为I=0.0453 0.00101c(nmol/L,R=0.9963,SD=0.0078);检出限为0·20nmol/L(13ng/L);在0.200~8.00μmol/L浓度范围内,线性方程为i=0.243 0.0864c(μmol/L,R=0·9983,SD=0.0188)。常见金属离子一般不干扰。方法简便快速,直接用于自来水实际样品的测定,加标回收率为95.4%~104.6%;RSD为3.36%,结果令人满意。