长期石油污染土壤中胡敏酸结构特征的研究

选择一口开采约20a的废弃油井,在距离井口0.5, 1.5, 3.5, 5.5和7.5 m处进行多点采样,应用元素分析、傅里叶变换红外光谱和固态13C核磁共振方法,研究了长期不同程度石油污染土壤中胡敏酸的结构特征。结果表明：随与油井口距离的减小,胡敏酸的C/H, O/C和(N+O)/C原子比值分别由0.74, 0.41和0.45增加到0.80, 0.83和0.88;红外光谱分析显示,胡敏酸的2 921, 2 851, 1 454 cm-1吸收峰相对强度下降,2 921/1 600比值由0.22减少到0.11;固态13C核磁共振分析显示,胡敏酸中烷基C的相对含量由49.9%下降到30.9%,而烷氧C、芳香C和羧基C的相对含量分别由20.1%, 13.1%和14.3%增加到28.0% 18.8%和19.3%。上述结果说明,随石油含量增加,胡敏酸的脂族性和疏水性降低,而芳香性和极性增强,其分子结构变得老化。为了促进受石油污染土壤的修复,有必要采取适当措施使其中老化的胡敏酸得以更新和活化。     

流动注射-化学发光法定量测定同一水域中的腐殖酸

采用流动注射-化学发光(FI-CL)这一灵敏的检测方法,通过条件实验与参数优化,优选了测定环境中痕量多羟基酚类化合物的发光体系,通过考察天然水体中的腐殖酸对化学发光-多羟基酚测定体系的影响,为来自于水及土壤中的实际样品中腐殖酸的检测提供了参考,建立了同一区域水体中腐殖酸的化学发光定量测定方法。 所得线性回归方程y=70.36x+540.1,相关系数r=0.995 4,线性范围为3～15 mg·L-1,检测限为0.749 mg·L-1,HA浓度为6 mg·L-1时的相对标准偏差(RSD)为1.08%。     

Changes in the Luminescent Properties of Humic Acids Induced by UV Radiation

Humic acids (HA) are complex, dark, paramagnetic biopolymers, ubiquitus in the soil and aquatic ecosystems. Due to their peculiar properties (multifluorophore system capable of excitation energy transfer, continuous featureless absorption over a wide spectral range, and paramagnetism), HA play an important role as an efficient target for UV solar radiation, O₂, and O₃—detrimental environmental factors which affect the Earth's biosphere. Photooxidation of HA causes changes in the absorption and luminescence properties of HA which may be of significant importance for environmental photophysics and photochemistry. We have studied effects of UV irradiation on the degradation of several commercial HA (Fluka, Merck, and Serva). Aqueous, aerated alkaline solutions of HA (0.1–0.4 g/L in 0.006–0.1 M Na₂CO₃) were irradiated with an electrodeless Hg (254-nm) lamp in a flow system during several hours. After different times of irradiation, solutions were assayed by means of fluorescence (Fl), absorption (UV–Vis), and chemiluminescence (CL) spectroscopy. The data obtained indicate that the free radical-mediated degradative photooxidation of HA macromolecules is accompanied by a very weak, long-lived chemiluminescence (340–800 nm), a gradual decrease in absorbancy with characteristic changes in color coefficients Q _4/6, Q _2.7/6.0, and Q _2.7/4.0, and an increase in the intensity of Fl emission (340- to 560-nm) and excitation (250- to 400-nm) spectra. Processes undergoing these changes are intrinsically associated with the generation of excited states and reactive oxygen species . These processes are expected to play a vital role in the natural environment, e.g., HA-photosensitized decomposition of xenobiotics and solar energy transfer in symbiotic hydrobionts.     

黑土腐殖酸的近红外光谱测定

研究了我国黑土腐殖酸碳含量及其光化学性质,并探索了利用近红外光谱分析法(near infrared spectroscopy, NIRS)对其进行预测的潜力。针对东北典型黑土带土壤样品,利用偏最小二乘法(PLSr)建立定量模型,并用独立样本对模型进行检验。结果表明,模型对腐殖酸碳、胡敏酸碳和富里酸碳含量的预测效果很好,NIRS对富里酸碳和胡敏酸碳的465 nm(E₄)和预测结果也较好,665 nm光密度(E₆)的预测达到可接受水平。胡敏酸碳和富里酸碳含量与SOC的相关性,高于其与NIRS模型预测值的相关性,二者光化学性质与SOC的相关性则低于其与模型预测值的相关性。NIRS在简化黑土腐殖酸碳、胡敏酸碳和富里酸碳含量和光密度测定领域具有很好的应用前景,且能够反映SOC性质方面的信息。     

猫爪草中的脂肪酸及有机酸的GC-MS分析

研究了用GC-MS法测定猫爪草中脂肪酸及有机酸的方法.河南产猫爪草块根粉碎后过20目筛,分别用石油醚(60～90℃)和乙醚回流提取6 h,提取液经浓缩后进行甲酯化,并由GC-MS法对其脂肪酸及有机酸的成分进行分析和鉴定.分析结果表明:两种提取剂的提取结果基本一致,猫爪草乙醚提取物中检测出含有23种物质,鉴定出其中的15种脂肪酸和有机酸,包括十四烷酸、十六烷酸、十八烷酸、二十烷酸、二十二烷酸、亚油酸、亚麻酸等,其中不饱和脂肪酸占58.19%,亚油酸占35.68%.     

Synthesis and Characterization of Ultraviolet Light-Emitting Organic Acids

Three ultraviolet light-emitting organic acids of 3,3′-(4-phenyl-4H-1,2,4-triazole-3,5-diyl)dibenzoic acid (Tz-1), 4,4′,4″-(4H-1,2,4-triazole-3,4,5-triyl)tribenzoic acid (Tz-2), and 4,4′-(4-(4′-carboxy-[1,1′-biphenyl]-4-yl)-4H-1,2,4-triazole-3,5-diyl)dibenzoic acid (Tz-3) were successfully synthesized and fully characterized by the ¹H NMR, the IR absorption spectra, and the X-ray single crystal diffraction. It was found that Tz-1, Tz-2, and Tz-3 could give out the ultraviolet photoluminescent spectra centered at 369 nm, 365 nm and 350 nm, respectively. The luminescence quantum yields of Tz-1 and Tz-2 were measured to be 0.20 and 0.14, respectively. Additionally, the density functional theory (DFT) and the time-dependent DFT calculations were also carried out for Tz-1, Tz-2, and Tz-3.     

Laser Desorption Mass Spectrometry of Some Organic Acids

Abstract

Positive and negative ion laser desorption (LD) mass spectra of organic acids are characterized by the emission of the quasimolecular ions (M+H)⁺ and (M-H)^?. Generation of (M+H)⁺ ions is interpreted as evidence for the occurence of high pressure proton transfer reactions in LD. Fragment ions can be rationalized by loss of stable neutral molecules from quasimolecular ions although decomposition may also be occuring prior to ionization. Features unique to LD, including the detection of pyrolysis products along with ions characteristic of the sample, are discussed in terms of the internal energy distribution in the irradiated microvolume. Negative ion mass spectra of acids are dominated by (M-H)^?, while positive ion spectra contain abundant fragment ions, underlining the utility of detecting negative ions for acidic compounds.     

Fourier Transform Surface-Enhanced Raman Spectra of Fulvic and Humic Acids Adsorbed on Au Electrodes

The Fourier transform Surface-enhanced Raman spectra of fulvic and humic acids from sea water adsorbed on an Au electrode were determined. At neutral and basic conditions, the humic acid was hung on the Au surface through its carbonyl groups, and the fulvic acid from the same source was adsorbed in both “end on” and “flat on” configurations. At acidic conditions, both of the fulvic and humic acids were adsorbed on the surfaces through their carboxylate and pyridine-like groups. The SERS behaviours of the humic and fulvic acids at different pH and potentials were from the difference of their chain sizes, charges and flexibility as well as the changes of their conformations. This preliminary study suggested that Fourier transform Surface-enhanced Raman spectroscopy could be used as a powerful probe with which to directly “see” humic substances at low concentrations.     

7-羟基香豆素与三种芳香族氨基酸作用的荧光光谱研究

运用荧光光谱和紫外光谱研究7-羟基香豆素UBM分别与色氨酸Trp,酪氨酸Tyr和苯丙氨酸Phe三种芳香族氨基酸的相互作用。结果表明在模拟人体生理条件下,UMB能引起上述氨基酸发生荧光猝灭,最大猝灭波长依次为347,303和282 nm,猝灭机制均为静态猝灭,相互之间均以摩尔比1：1形成了复合物,且得到两种温度下UMB与Trp,Tyr和Phe反应的表观平衡常数K_c分别为298.15 K时2.993×106,7.858×104和1.186×103 L·mol-1,310.15 K时2.702×104,1.063×105和8.352×103 L·mol-1。热力学函数变化表明UMB与以上三种氨基酸结合作用较强,其中UMB-Trp相互作用力是氢键或范德华力,UMB-Tyr和UMB-Phe相互作用主要以疏水作用为主,同时都可能存在偶极-偶极之间的相互作用。     

铟(Ⅲ)荧光探针与核酸作用机理的光谱研究

应用荧光和紫外可见光谱技术 ,研究了铟 ( )荧光探针与核酸作用的影响因素 ,探讨了体系的作用机理。在 p H7.5和低离子强度条件下 ,荧光探针与核酸发生了沟内结合作用 ,对体系产生了明显的荧光增强作用     

红外光谱结合二维相关分析研究堆肥过程腐殖酸演化规律

堆肥材料中腐殖酸的组成和结构直接影响堆肥产品品质和腐熟度。为研究堆肥腐殖酸的组成和形成过程,进行了生活垃圾堆肥并提取了不同堆肥阶段样品中的胡敏酸和富里酸,采用红外光谱和二维相关分析,探讨了堆肥过程胡敏酸、富里酸的组成、结构及随时间演化规律。红外光谱结果显示,堆肥胡敏酸组成复杂,在2 917～2 924,2 844～2 852,2 549,1 662,1 566,1 454,1 398,1 351,990～1 063,839,711 cm-1均出现了吸收峰;相对于胡敏酸,堆肥富里酸结构简单,仅在1 725,1 637,990 cm-1出现了吸收峰。上述吸收峰的出现表明堆肥胡敏酸和富里酸均含有木质素来源的苯环和糖类结构,但胡敏酸还含有丰富的脂族和蛋白类结构,这些在富里酸中含量较低;堆肥过程糖类、脂类、蛋白类及木质素结构均发生了降解,但是在胡敏酸和富里酸中它们的降解优先顺序不同。二维相关光谱分析结果表明,胡敏酸中降解先后顺序为脂肪类—蛋白类—多糖类和木质素,而富里酸中为蛋白质—多糖和脂肪类,降解过程均生成了羧酸、酮类和酯类结构,其中羧酸类物质一部分在堆肥中形成了碳酸盐。研究结果表明,红外光谱结合二维相关分析不仅可以获得堆肥腐殖酸官能团组成,还可以揭示堆肥过程这些官能团降解顺序,确定堆肥腐殖酸合成机制和动力学过程。     

小分子有机酸改性尿素的多谱学分子结构表征

尿素是我国主要的氮肥品种,但其活性高,在土壤中水解后极易通过挥发和淋洗损失,利用率低,造成养分资源浪费并污染环境.使用有机酸对尿素进行改性可以延缓尿素分解,提高尿素利用率,但有机酸与尿素的结合方式及其增效机理尚不明确.研究中选取柠檬酸和水杨酸两种小分子有机酸作为添加剂,分别加入到熔融尿素中,获得柠檬酸尿素与水杨酸尿素....     

Spectroscopic Study on the Interaction of Pyronine Y with Nucleic Acids and Its Analytical Application

ABSTRACT

The interaction of pyronine Y (PY) with nucleic acids was studied by resonance Rayleigh scattering (RRS) for nucleic acid detection. The enhanced RRS intensity of nucleic acids reacted with PY was proportional to the concentration of nucleic acids in the ranges of 27.0–625 ng ml^?1 for fish sperm DNA, 39.0–500 ng ml^?1 for calf thymus DNA, and 59.0–375 ng ml^?1 for yeast RNA. The limits of determination were 0.2 ng ml^?1 for fish sperm DNA, 0.6 ng ml^?1 for calf thymus DNA, and 0.7 ng ml^?1 for yeast RNA. The method had been successfully applied to the quick determination of nucleic acids in synthetic and natural samples.     

棕壤与褐土刺槐林下土壤腐殖质组分的傅里叶变换红外光谱分析

森林土壤富含不同组分和功能的有机碳。该研究以棕壤和褐土45年林龄的刺槐林下表层及底层土壤为对象,研究其林下土壤腐殖酸组分在不同土壤类型和不同土层间的差异和变换。褐土和棕壤表层及底层土壤分别定义为CO和CA,BO和BA。应用傅里叶变换红外光谱对土壤腐殖质组分的富里酸(FA)、胡敏酸(HA)和胡敏素(HM)进行了分析。结果表明富里酸主要吸收峰为3 400 cm-1处的碳水化合物中—OH形成的氢键伸缩振动,1 655 cm-1处的芳香环CC伸缩振动,1 110 cm-1处的脂族C—OH伸缩振动。与富里酸相比,胡敏酸所含官能团与其相似,差异在于其吸收峰强度较弱。胡敏素在1 110 cm-1处的脂族C—OH伸缩振动和1 030 cm-1处多糖或类多糖物质的C—O伸缩振动较胡敏酸此处的峰吸收强度强。根据分析,表层土壤腐殖质官能团结构较底层土壤多且吸收强度强。另外,富里酸不同物质官能团数量及强度受土壤类型和土壤深度的影响较胡敏酸和胡敏素小。根据不同吸收峰对比分析发现,富里酸组分的芳化程度较强,而胡敏酸和胡敏素的芳化作用仅表层土壤程度较强。不同土壤类型胡敏酸组分分析表明,棕壤表层土壤芳族和脂肪族物质吸收强度明显高于褐土。综上,土壤类型和土层显著影响45年林龄的刺槐林下土壤腐殖质组分,尤其是胡敏酸和胡敏素组分。     

激光诱导纳秒时间分辨荧光猝灭法原位研究菲及烷基菲与腐植酸相互作用

利用激光诱导纳秒时间分辨荧光(laser-induced nanosecond time-resolved fluorescence,LITRF)猝灭法原位研究腐植酸(humic acid,HA)分别与母环多环芳烃(polycyclic aromatic hydrocarbons,PAHs)菲(phenanthrene,Phe)及烷基PAHs 9-乙基菲(9-Ethylphenanthrene,9-EP)和惹稀(retene,Ret)相互作用,考察HA对母环及烷基PAHs结合特性差异与机制,对了解PAHs环境行为及生物有效性有重要意义。结果表明,通过改变延迟时间(50ns)可有效消除HA荧光干扰,实现游离Phe,9-EP及Ret浓度直接测定。利用Freundlich非线性等温吸附模型描述Phe,9-EP和Ret与HA结合特性,LITRF猝灭法与传统荧光法获得的模型拟合参数及单点结合系数结果一致。其中,参数n小于1,表明Phe,9-EP及Ret与HA均以非线性形式结合,且9-EP和Ret非线性程度高于Phe;相同给定平衡浓度下,HA与9-EP和Ret单点结合系数KOC大于Phe,而9-EP和Ret结合能力相近,且PAHs与HA结合系数均随给定浓度增加而降低。疏水性、取代基及与HA疏水空腔适应能力决定特定PAHs与HA结合特性。通过荧光寿命分析,HA存在下Phe,9-EP和Ret寿命分别为36.90,35.34和35.13ns,与未加入HA时的36.36,35.34和35.84ns无明显差异,表明Phe,9-EP和Ret与HA间的荧光猝灭以静态过程为主。LITRF猝灭法可快速有效原位研究PAHs与HA相互作用,有助于实现PAHs生态风险原位评估。     

Interaction Energy in Polymer Blends Containing N-1-Alkylitaconamic Acids Moiety

Abstract

Analysis of the interaction energy of N-1-alkylitaconamic acids to explain the miscibility behavior of polymers containing this moiety is performed. In order to calculate the interaction energy, many conformations of the N-1-alkylitaconamic acid fragments containing ethyl, propyl, butyl, hexyl, octyl, decyl, and dodecyl were selected randomly from molecular dynamic simulations. It was assumed that miscibility and other properties are determined by the enthalpy of mixing, ΔH_mix, that ΔH_mix is dominated by the local interactions between segments of the polymer chains, and, furthermore, that PΔV_mix contribution can be ignored. The polymer miscibility is discussed by using interaction energies calculated from molecular mechanics studies on pairs of small polymer fragments. By this method and by using the Blend package (Accelrys), good correlations between the interaction energy and the Gordon Taylor constant (K_GT) values for blends of poly(N-1-alkylitaconamic acids) and poly(4-vinylpyridine) previously reported are obtained. The analysis of the energies shows that Coulombic energies decay rapidly being almost “zero” as the side-chain lengths reach near eight carbon atoms. On the contrary, the van der Waals interaction (VDW) energies decay in a linear way as the length of the side chain increases. The slope of the VDW energies is an estimation of the energetic contribution per methylene unit to the blending process. The slope in this case is 570 cal/mol, which is a value very close to that experimentally reported in the literature for related systems. The blend energy was calculated, and good correlation with the experimental results is obtained.     

碳纳米管与有机小分子官能团相互作用的分子动力学研究

利用Material Studio软件先对不同半径的碳纳米管进行结构优化,再对优化后的纳米管进行分子动力学模拟。得到如下结论：经过优化后小半径纳米管结构基本不变,但是随着半径增大纳米管形变越来越明显。同时通过对多根管簇研究后发现也有相似动力学特性。在以上纳米管结构外面加上一定密度随机排列的对苯二甲酸二辛酯（DOTP）有机分子,发现DOTP有机分子与不同结构、不同半径的纳米管之间都存在相互作用,纳米管半径越大相互作用力也越大,同时DOTP分子在纳米管周围排列也逐渐从无序趋于有序。通过计算以上结构的径向分布函数（RDF）等热力学特性,定性和定量地验证了以上结果。     

β-二酮型高分子纳米微球与核酸相互作用的共振光散射光谱及分析应用

在超声辐射下 ,过氧化氢氧化降解聚乙烯醇 (PVA) ,制得与 Zn2 形成配位体的纳米尺寸的 β-二酮型高分子微球 (Zn- PVK)。对 Zn- PVK的共振光散射 (RLS)性质研究发现 ,Zn- PVK与核酸形成缔合物时将导致 Zn- PVK的 RLS信号急剧增加 ,据此建立一种用 RLS信号测定痕量核酸的新方法。方法的抗干扰能力强 ,用于合成样品的分析 ,结果令人满意。     

基于深度张量神经网络预测有机分子的相互作用能

分子的相互作用在分子动力学模拟过程中起着关键的作用. 受限于计算资源,大分子的长时间尺度的相互作用能无法通过量化计算实现. 本文采用一种深度学习框架-深度张量神经网络来预测三个有机分子相关体系中量化精度的相互作用能. 其中,分子的几何结构和原子类型作为网络的输入用于预测相互作用能. 通过分层生成的数据集合实现了网络中隐层参数的优化和训练. 相互作用能的预测结果显示,深度张量神经网络可以在较短的时间内,在1 kcal/mol的平均绝对误差的范围内准确预测分子间的相互作用能. 这一过程提高了计算效率,并为计算相互作用能提供了可靠的计算框架.