共聚焦拉曼光谱研究过饱和硝酸铵液滴中NH4+, NO3- 和H2O之间的相互作用

将硝酸铵液滴沉积在石英基底上,通过降低该液滴周围环境的相对湿度,测定了该液滴由低浓度直至过饱和状态下高信噪比的拉曼光谱.其中,相对湿度的变化可以精确控制液滴浓度的改变.在相对湿度(RH)由72.1%降低至37.9%的过程中,硝酸铵液滴v1-NO-3峰位保持在1048cm-1,半峰宽为10cm-1.该现象表明NO-3周围的水分子被NH4+取代后不会对v1-NO-3造成影响,说明水分子和NH4+所形成的氢键具有相同的强度.对2500-4000cm-1范围内的拉曼光谱进行成分分析,2890、3090、3140、3220、3402及3507cm-1分别被指认为NH+4伞状弯曲振动的泛频、NH+4伞状弯曲振动与摇摆振动的组合谱带、NH+4的对称伸缩振动、NH+4的反对称伸缩振动、水峰中强氢键成分和弱氢键成分.从拟合结果得出:强氢键在氢键结构中所占百分含量随液滴相对湿度的降低而减少,弱氢键所占百分含量随液滴相对湿度的降低而增加.该变化趋势是NO-3和NH+4之间复杂相互作用的结果.     

FTIR-ATR原位观测Mg(NO3)2气溶胶的潮解和风化过程

利用FTIR-ATR(傅里叶变换红外-衰减全反射)原位光谱技术在分子水平上研究了ZnSe基底上Mg(NO3)2气溶胶颗粒的潮解和风化过程.根据FTIR-ATR光谱的演变可知,Mg(NO3)2气溶胶在潮解过程中经历了复杂的相变:相对湿度(relative humidity,RH)接近3%时,Mg(NO3)2气溶胶颗粒为无定型水合物;稍微升高相对湿度,无定型颗粒转化为Mg(NO3)2·nH2O(n≤5)晶体,并且在其表面逐渐形成热力学稳定的Mg(NO3)2·6H2O晶体;相对湿度达到Mg(NO3)2·6H2O的饱和点(53%RH)时,Mg(NO3)2·6H2O开始溶解,同时,内核Mg(NO3)2·nH2O(n≤5)晶体在其表面持续转化为Mg(NO3)2·6H2O晶体,导致固态气溶胶颗粒全部潮解时的相对湿度延迟到76%.风化过程中,Mg(NO3)2液滴随相对湿度的降低逐渐失水进入过饱和区域;相对湿度降至5%以下时,形成无定形颗粒.在过饱和Mg(NO3)2液滴的FFIR-ATR光谱中,NO-3对称伸缩振动(v1-NO3-)的吸收强度明显增加,是溶剂共享离子对,甚至接触离子对持续形成的结果.     

高时空分辨率研究海盐液滴快速风化过程

以高速摄像仪与显微拉曼光谱联用研究聚四氟(疏水)乙烯基底和石英(亲水)基底上的单个海水液滴的快速风化过程.海水液滴风化的形貌图像达到毫秒时间分辨率和微米空间分辨率.通入干氮气后海水液滴在石英基底上发生快速风化过程,首先析出Na2Ca5(SO4)6·3H2O和Na2xCa8-x(SO4)6·3H2O(0＜x＜1)晶体,然后析出NaCI晶体,最后析出KMgCl3·6H2O晶体.我们发现在快速降低湿度的过程中析出钙钠复盐,在缓慢降低湿度的过程中析出CaSO4·2H2O,并已经确定各种结晶产物的位置以及Na2Ca5(SO4)6·3H2O和CaSO4· 2H2O两种晶体的生长速率,并在聚四氟乙烯基底上观察到中空结构的海盐颗粒.     

AOT/水/甲苯微乳体系的第二维里系数和液滴间的相互作用

在一系列温度下通过对水与丁二酸双(2-乙基己基)酯磺酸钠(AOT)摩尔比为12、不同浓度的AOT/水/甲苯微乳液进行静态光散射测量, 获得液滴的相对分子质量、AOT的聚集数、液滴半径和不同温度下的第二维里系数. 利用第二维里系数与温度的关系获得液滴的相互作用焓和熵, 分别为-4.03×10⁴ J·mol^-1和-139.8 J·mol^-1·K^-1, 说明AOT/水/甲苯微乳液滴间表面活性剂疏水链相互交叉渗透的能量变化为负值, 交叉渗透为焓驱动.     

基于渗透脱水的自动化蛋白质结晶高通量筛选芯片

构建了一种基于渗透脱水模式的自动进样微流控结晶芯片. 该芯片通过真空预脱气将包含蛋白质和结晶剂的液滴自动分配至结晶微腔阵列中, 然后利用集成的一排包含不同浓度盐溶液的透析管道, 通过渗透脱水方式经一层聚二甲基硅氧烷(PDMS)膜实现液滴的逐渐浓缩, 使之趋于过饱和状态, 进而形成结晶. 此芯片可一次筛选较宽范围的过饱和状态, 实现蛋白质结晶的快速优化. 利用模式蛋白溶菌酶的结晶实验验证了该芯片的性能.     

碱性二苯基萘基甲烷染料褪色光度法测定透明质酸钠

在弱酸性介质中 ,碱性二苯基萘基甲烷染料与透明质酸钠作用形成结合产物时将导致溶液光吸收发生变化 ,在 5 85～ 6 1 6nm附近褪色且吸光度差 (ΔA)值与透明质酸钠浓度成正比 ,在 0 .1～ 2 .5mg/L(维多利亚蓝B)、0 .5～ 2 .0mg/L(夜蓝 )和 0 .1～ 0 .6mg/L(维多利亚蓝 4R)范围内符合Beer定律 ,表观摩尔吸光系数达 1 .5 1× 1 0 8～ 5 .5 2× 1 0 8L·mol-1 ·cm-1 (透明质酸钠的分子量以 5× 1 0 5计 ) ,其中 ,维多利亚蓝 4R灵敏度最高。据此 ,建立了一种新的测定透明质酸钠的分光光度法。该法简便、快速 ,灵敏度高 ,选择性好。应用于润舒氯霉素滴眼液、润洁滴眼露和施沛特注射液中透明质酸钠的测定 ,结果满意     

乙基紫褪色分光光度法测定七叶皂苷钠

在pH 4.1的BR缓冲溶液中,乙基紫(EV)与七叶皂苷钠(SA)作用,形成离子缔合物,溶液颜色发生明显褪色.其最大褪色波长位于594 nm处,七叶皂苷钠的质量浓度与褪色强度呈正比,七叶皂苷钠的质量浓度在0.15～35.0μg/mL范围内遵守比尔定律,相关系数为R=0.9995,摩尔吸光系数为2.5×104L·mol-1·cm-1,检出限为45.8 ng/mL.该方法已用于片剂和尿样中七叶皂苷钠的测定.     

毛冬青甲素的核磁共振法分析

采用^1H、^13C、DEPT(无畸变极化转移增益法)、^1H-^1 COSY(氢-氢化学位移相关谱)、HMQC(异核多量子相关谱)、HMBC(异核多键相关谱)、NOESY(二维核欧沃豪斯效应谱)等多种NMR分析方法,对毛冬青甲素的^1H和^13C NMR谱信号进行了归属;并对生产过程常同时存在的丁二酸二钠也进行了谱线归属,提出通过^1H NMR法对产品中的丁二酸二钠进行定量测定。为其结构鉴定和生产过程中的质量控制提供了重要依据。     

2-噻吩乙醛酸-三苯基氧化膦-铕配合物的合成、结构表征及荧光性能的研究

用硝酸铕、2-噻吩乙醛酸(HL)和三苯基氧化膦(TPPO)合成了一种新型固体发光配合物;用元素分析、电导率、红外光谱和核磁共振确定了该配合物的分子式为EuL3TPPPO((H2O)2;在室温下测定了该配合物的荧光激发光谱和发射光谱;配合物中Eu(Ⅲ)离子的3个主要跃迁5D0→7F1,5D0→7F2和5D0→7F4分别位于593.4,618.8和699.4 nm.该固体配合物于室温下被紫外灯照射可以发出很强的红色荧光.IR光谱中2-噻吩乙醛酸在与稀土铕离子形成配合物后,vas(-COO-)由钠盐的1632 cm-1移至1612 cm-1,vs(-COO-)由1389 cm-1移至1409cm-1;vc=o(α-酮基)由HL的1654 cm-1移至1662 cm-1.配合物的vEu-o吸收峰出现在541 cm-1.在1HNMR谱图中,噻吩环上的3个氢原子的化学位移在形成配合物后移向高场;三苯基氧化膦中苯环上5种不同环境的质子的化学位移在形成配合物后向低场移动.TG分析证明,该固态配合物于空气中在常温至190℃以内是稳定的.     

碱性三苯甲烷染料褪色分光光度法测定藻酸钠

在弱酸性的HAc-NaAc缓冲溶液中,藻酸钠与乙基紫、结晶紫和甲基紫等三苯甲烷碱性染料发生反应,形成结合产物使染料发生褪色,且对于不同的染料,最大褪色波长分别为594 nm(乙基紫体系)、584 nm(结晶紫、甲基紫体系)、616 nm(孔雀石绿体系)。藻酸钠浓度分别在0~5.0 mg/L(乙基紫、甲基紫体系)0、~3.0 mg/L(结晶紫体系)0、~2.0 mg/L(孔雀石绿体系)范围内符合比耳定律;摩尔吸光系数根据染料的不同在3.6×105~4.8×106L.mol-1.cm-1之间,其中以乙基紫体系最灵敏,对藻酸钠的检出限为29 ng/mL。以乙基紫体系为例研究了共存物质的影响。此法灵敏度高,选择性好,用于含藻酸钠的可立凝样品的分析测定,结果满意。     

Removal of organic acid salts from simulated fermentation broth containing succinate by nanofiltration

In microbial cultures for the production of sodium succinate, often monovalent salts of sodium formate, sodium acetate and/or sodium lactate are produced as major by-products. In this study, nanofiltration (NF) was employed for the recovery of sodium succinate and the removal of by-products from simulated fermentation broth. In a series of preliminary experiments with synthetic single-salt solutions, five nanofiltration membranes were evaluated, and NF45 and ESNA1 membranes with a relatively low rejection to monovalent anions were selected for the subsequent experiments. The rejection of each salt at various fluxes was measured for single, binary, ternary and quaternary organic acid salts solutions containing succinate, formate, acetate, and/or lactate, simulating a real fermentation broth. Succinate rejection in multi-salt solutions was observed much higher than that in its single-salt solution, which was quite opposite to the cases of the monovalent acid salts involved. This could be well described by the facilitated transport of the monovalent anions due to Donnan effect in the presence of succinate, a divalent anion. Finally, nanofitration of a quaternary salts solution in a diafiltration mode was carried out for 36 h. With time, the rejection of succinate increased and the rejection of the by-products drastically decreased as the concentration ratio of succinate to by-products increased. From the extrapolation using a diafiltration model developed in this study, it was expected that almost complete removal of by-products was possible with no significant loss of succinate.     

DC-dielectrophoretic separation of microparticles using an oil droplet obstacle

A new dielectrophoretic particle separation method is demonstrated and examined in the following experimental study. Current electrodeless dielectrophoretic (DEP) separation techniques utilize insulating solid obstacles in a DC or low-frequency AC field, while this novel method employs an oil droplet acting as an insulating hurdle between two electrodes. When particles move in a non-uniform DC field locally formed by the droplet, they are exposed to a negative DEP force linearly dependent on their volume, which allows the particle separation by size. Since the size of the droplet can be dynamically changed, the electric field gradient, and hence DEP force, becomes easily controllable and adjustable to various separation parameters. By adjusting the droplet size, particles of three different diameter sizes, 1 microm, 5.7 microm and 15.7 microm, were successfully separated in a PDMS microfluidic chip, under applied field strength in the range from 80 V cm-1 to 240 V cm-1. A very effective separation was realized at the low field strength, since the electric field gradient was proved to be a more significant parameter for particle discrimination than the applied voltage. By utilizing low strength fields and adaptable field gradient, this method can also be applied to the separation of biological samples that are generally very sensitive to high electric potential.     

Measurement and Correlation Solubility of Sodium Succinate in Binary Mixed Solvents of Water + (Methanol or Ethanol) Mixtures

The solubility of sodium succinate in binary solvent mixtures was measured by an analytical stirred-flask method in the temperature range 278.15–318.15 K at atmospheric pressure. It was found that the solubility of sodium succinate in the system increased with increasing temperature and decreased with the increasing mass fractions of methanol or ethanol. The modified Apelblat equation, the Buchwski–Ksiazaczak λh equation and the combined nearly ideal binary solvent/Redlich–Kister (CNIBS/R–K) equation were proposed for correlating the experimental data. The modified Apelblat equation was found to regress the solubility data much better than the Buchwski–Ksiazaczak equation and the CNIBS/R–K equation in a binary solvent system. The dissolution enthalpy and dissolution entropy of sodium succinate were calculated from the solubility data, using the Van’t Hoff equation. The experiment results and correlation models could be used as essential data in the purification of sodium succinate.     

无定型氧化硅转变为α-方石英的振动光谱

红外和喇曼光谱是分子结构信息的重要来源,也是研究表面和催化问题的强有力手段,常用来表征活性中心及吸附物种的结构．为提高稳定性,催化剂一般都要经过焙烧处理,在焙烧过程中,载体结构可能会发生变化,有时还会形成一定的晶相．载体结构变化时,一般会伴随振动光谱的变化,因此在利用振动光谱研究催化体系时,弄清载体的振动光谱是十分必要的．二氧化硅是最常用的催化剂载体之一,但它具有比较多的结构形式,除无定型氧化硅中硅氧四面体可连接成不同的结构外,它还具有石英、鳞石英、方石英等多个晶相系列．对氧化硅的不同结构形式,…     

水／AOT／正庚烷微乳体系中磺酸根水化作用的FT—IR研究

运用傅立叶变换红外光谱（FT－IR）对水／琥珀酸（乙基已基）磺酸钠（AOT）／正庚烷微乳体系中磺酸根的水化作用进行了研究．由于微乳体系中水分子与表面活性剂分子的相互作用，S＝O对称伸缩振动的红外吸收峰向低频方向移动．体系中的加水量W0（水与AOT的摩尔比）由0.5增大至25时，磺酸根对称伸缩振动的红外吸收峰由1051．39cm－1向低频移动至1046．15cm－1．同时，由于Na 的不对称作用，AOT分子中磺酸根反对称伸缩振动分裂成两个吸收峰，分别位于正215cm-1及1245cm－1附近，两个劈裂峰的距离及各自的峰面积均随体系中加水量的变化而变化，应用二阶导数、傅立叶退卷积及曲线拟会等分辨率增强技术可更清楚地反映出这个二重峰的变化情况．固体AOT分子中碳酸根反对称伸缩振动分裂的两个峰之间频率的差值约为42cm－1，形成微乳液以后，这两个峰的差值变小，W0为20时，这两个峰频率的差值逐渐减小到29cm-1，这些变化与磺酸根的水化程度直接相关     

A Raman spectroscopic study of the uranyl phosphate mineral bergenite

Raman spectroscopy at 298 and 77 K of bergenite has been used to characterise this uranyl phosphate mineral. Bands at 995, 971 and 961 cm-1 (298 K) and 1006, 996, 971, 960 and 948 cm-1 (77K) are assigned to the nu1(PO4)3- symmetric stretching vibration. Three bands at 1059, 1107 and 1152 cm-1 (298 K) and 1061, 1114 and 1164 cm-1 (77 K) are attributed to the nu3(PO4)3- antisymmetric stretching vibrations. Two bands at 810 and 798 cm-1 (298 K) and 812 and 800 cm-1 (77 K) are attributed to the nu1 symmetric stretching vibration of the (UO2)2+ units. Bands at 860 cm-1 (298 K) and 866 cm-1 (77 K) are assigned to the nu3 antisymmetric stretching vibrations of the (UO2)2+ units. UO bond lengths in uranyls, calculated using the wavenumbers of the nu1 and nu3(UO2)2+ vibrations with empirical relations by Bartlett and Cooney, are in agreement with the X-ray single crystal structure data. Bands at (444, 432, 408 cm-1) (298 K), and (446, 434, 410 and 393 cm-1) (77 K) are assigned to the split doubly degenerate nu2(PO4)3- in-plane bending vibrations. The band at 547 cm-1 (298 K) and 549 cm-1 (77 K) are attributed to the nu4(PO4)3- out-of-plane bending vibrations. Raman bands at 3607, 3459, 3295 and 2944 cm-1 are attributed to water stretching vibrations and enable the calculation of hydrogen bond distances of >3.2, 2.847, 2.740 and 2.637 A. These bands prove the presence of structurally nonequivalent hydrogen bonded water molecules in the structure of bergenite.     

Vibrational studies on the selective solvation of Na+ and ClO3- ions in dimethylformamide-formamide mixture

Raman and infrared spectra of sodium chlorate in binary mixture of N,N-dimethylformamide (DMF) and formamide (FA) were obtained. The addition of FA to the NaClO3-DMF system allow us to observe a new band at 1709 cm-1. This has been possible since the large dissociation of Na+ and ClO3- ions produced by the addition of FA helps to observe the coordination effect of DMF on the Na+ ions, in full agreement with the Gutmann donor number of this later. Quantitative measurements performed in the CO stretching region in the binary mixture give a solvation number value for the sodium cation equal at 3 in full agreement with others authors. In the NH stretching region of FA, the arising of the 3580 cm-1 band is assigned to FA-ClO3- interactions via hydrogen bonding. In addition, our results show that the solvation number of the sodium cation remain constant in all concentration range studied. Such fact suggests that mixture of solvents with considerable differences in the donor-acceptor characters can be used to prepare electrolyte solutions where the ion pairs formation seems uncertain.     

FTIR spectra of plasticized grafted natural rubber-LiCF3SO3 electrolytes

Chemical modification of natural rubber (NR) has frequently been attempted to improve the performance in specific application. 30% poly(methyl metacrylate) (PMMA) grafted into NR (MG30) has been explored as a potential candidate for polymer electrolytes. The complexation effect of salt and plasticizer in polymer host electrolytes had been investigated using FTIR. The carbonyl stretch of MG30 locates at 1729 cm-1, with the addition of lithium trimethanesulfonate (LiCF3SO3) salt, new band evolves at lower frequency region at 1643-1645 cm-1. The nondegenerate vibrational mode of nus(SO3) of salted electrolytes appearing at 1031-1034 cm-1 comes from 'free' trimethanesulfonate anions and the 1040-1046 cm-1 absorption from the monodentate ion paired with triflates. These indicate MG30-salt interaction. When MG30 and ethylene carbonate (EC) formed film, the CH3 asymmetric bend of MG30 appearing at 1447cm-1 is shifted to 1449 cm-1 in the EC-polymer complex. The CO stretching at 1729 cm-1 also shifted to 1728 cm-1. Hence, the EC-MG30 system is complexed to each other. EC-LiCF3SO3 interactions are indicated by the shifting of CO bending band of EC from 718 cm-1 being shifted to 720 cm-1 in the complex. In Li+-EC interaction where the ring breathing region at 897 cm-1 in EC has shifted to 899 cm-1 in EC-salt spectrum. The band appearing at 1643-1645 cm-1 due to the coordination of Li+<--O-C is still under observation and new peaks at 1779 and 1809 cm-1 are responsible to the carbonyl stretches of EC in plasticized salt-polymer electrolytes.     

Meso-四(对-磺基苯基)卟啉光度法测定螺旋藻中的痕量锌

在pH=4．5的乙酸-乙酸钠缓冲介质中，锌和meso-四-（对磺基苯基）卟啉生成1：l的黄色配合物，λmax=421nm，ε=4.34×105L·mol-1·cm-1。该法可不经分离直接测定螺旋藻中的锌,结果满意。