Effects of different alkali metal ions on the cationization of poly(ethylene glycol)s in matrix-assisted laser desorption/ionization mass spectrometry: a new selectivity parameter

The cationization of poly(ethylene glycol)s, PEG 4000 and PEG 6000, under matrix-assisted laser desorption/ionization conditions was studied by using different concentration ratios of the sodium ion, as the reference ion, and another alkali metal ion (Li(+), K(+), Rb(+), Cs(+)). A linear correlation was found between the intensity ratio of the sodiated PEGs and PEGs cationized with alkali metal ions versus the initial concentration ratio of sodium and alkali metal ions. The slopes of these straight lines are proposed as a novel selectivity ratio for the ionization process. The intensity distribution of the cationized PEGs was also investigated. It was found that the cationized oligomers follow Poisson statistics. The M(n) and M(w) values were also evaluated. An explanation for the observed effects is given.     

Etude thermoanalytique et spectrale de l'interaction lorazepam/PEG 6000

Résumé The solubility and rate of dissolution of a poorly-soluble active principle are of importance when substances are destined for oral administration. Physical blends in wich drug and carrier are able to form particular compositions, such as a eutectic, may exibit an increased rate of dissolution. In this work the interactions lorazepam and PEG 6000, were examined, the particular thermal behaviour of lorazepam being taken into account. An eutectic was obtained and its composition was studied by means of differential scanning calorimetry, thermomicroscopy, infrared spectroscopy and X-ray methods.

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Zusammenfassung Bei der oralen Darreichung von Substanzen ist die L?slichkeit und Aufl?sungsgeschwindigkeit schlechtl?slicher aktiver Komponenten von gro?er Bedeutung. Physikalische Gemische, in denen Wirkstoffe und Tr?gersubstanzen besondere Zusammensetzungen wie zum Beispiel Eutektika zu bilden in der Lage sind, k?nnen eine erh?hte Aufl?sungsgeschwindigkeit zeigen. Vorliegend wird die Wechselwirkung zwischen Lorazepam und PEG 6000 untersucht, wobei das besondere thermische Verhalten von Lorazepam berücksichtigt wurde. Es wurde ein Eutektikum erhalten und dessen Zusammensetzung mittels DSC, Thermomikroskopie, Infrarotspektroskopie und R?ntgenmethoden untersucht.

     

PEG6000溶液超声化学反应机理的初步研究

采用不同电功率的超声波处理了聚乙二醇(PEG6000)溶液。凝胶渗透色谱(GPC)分析超声处理后的PEG溶液发现,当超声电功率超过250W时,PEG分子量随超声波作用强度的增大而减少,随超声波作用时间的延长而增大;在电功率超过250W超声波作用下,傅立叶红外光谱(FT-IR)分析表明,组成PEG的单体没有明显改变,但是,羟基含量分析表明,PEG固体样品中的羟基含量有所减少。结合实验结果,根据高分子化学、有机化学和超声化学中相关理论对PEG超声化学反应机理进行了探讨,认为:当超声波作用于PEG溶液时,同时存在有PEG的缩水聚合反应和自由基降解反应,当频率为20-25kHz、电功率为250-600W的超声作用于PEG6000溶液时,缩水聚合反应占主导地位。     

{110}晶面取向Ag3PO4多面体的水热制备及可见光催化活性

采用简易水热法在聚乙二醇-6000 (PEG-6000)辅助下合成了Ag₃PO₄多面体.系统考察了水热反应温度、时间及PEG-6000用量对产物形貌和结构的影响.通过X射线衍射(XRD),扫描电子显微镜(SEM),紫外-可见漫反射光谱(UV-Vis DRS)和荧光(PL)光谱等测试手段对光催化剂进行了表征.结果表明,适宜的水热温度及PEG-6000用量是制备具有{110}活性晶面取向Ag₃PO₄多面体的必要条件,该多面体通过纳米颗粒的Ostwald熟化效应生长而成.可见光催化降解罗丹明B (RhB)的实验表明,该Ag₃PO₄多面体活性明显优于其它水热条件下所制备的非{110}取向晶面样品和离子交换法所得纳米颗粒,其降解反应速率常数(k)为离子交换法所得Ag₃PO₄纳米颗粒的8.3倍.总有机碳含量(TOC)及循环实验证明,该Ag₃PO₄多面体可以有效地矿化RhB并保持较好的循环稳定性.活性自由基捕获实验表明,空穴(h⁺)和羟基自由基(·OH)是光催化氧化的主要活性物种.结合活性物种的氧化还原电位以及Ag₃PO₄的能带结构分析,提出了催化反应界面光生电子-空穴(e^--h⁺)对的分离及转移机制.     

PEG-6000对Mn-Zn铁氧体纳米粉体烧结特性的影响

利用化学共沉淀回流法制备Mn-Zn铁氧体纳米粉体的过程中,加入适量PEG-6000,试图通过在纳米颗粒表面形成一保护层以起到抑制其团聚的目的.研究结果表明,PEG-6000的加入不仅减小了纳米粒子的尺寸,还有效缓解了它们的团聚.将这些纳米Mn-Zn铁氧体粉体进行成型烧结,材料的起始磁导率随烧结温度的升高呈抛物线规律变化,并于1200 ℃达到最大值.而且添加PEG-6000的样品起始磁导率比未添加的提高了约20;.导致这一变化的原因应归咎于纳米粉体稳定性的改善以及烧结后材料内部组织均匀度的提高和晶粒尺寸的减小.     

Infrared band intensities: a comparative study of the transition moment matrix elements for the fundamental and overtones: Part II. Application to CO,HCl and OH

The various expressions considered in Part I for the transition moment matrix elements of fundamental and first two overtones are applied to carbon monoxide. The coefficients a_ij in the expressions R^io = Σa_ijp_j (where R^io is the transition moment integral for the O → i vibrational transition and p_j is the dipole moment derivative ?^jP/?XXX^j, XXX = (r — r_e)/r_e, r_e is equilibrium bond distance) are reported for i,j = 1, 2, 3. It is found that these coefficients do not vary by more than 5% when compared for the same i,j values in various expressions irrespective of the most exhaustive treatments used in deriving the original expressions. On the basis of the values of the coefficients obtained for CO, generalisations have been suggested on the effects of inclusion of mechanical and electrical anharmonicity to the intensities of fundamental and first two overtones. It is generally observed that the contribution of p'₁, is about 100 fold more than the contribution of p'₂, for R¹⁰. On the other hand the contributions of p'₁, and p, for R²⁰ and R³⁰ are of nearly equal magnitude but opposite in sign. The contribution of p'₁ to R¹⁰ is much higher than its contribution to R²⁰ and R²⁰. The various observations lead us to conclude that, whereas the effect of inclusion of mechanical anharmonicity on the intensity of the fundamental band is negligible, this effect is almost comparable to the effect of inclusion of electrical anharmonicity for the first two overtones. Simple forms of the a_ij expressions are applied to HC1 and OH to demonstrate the effect of variation of molecular constants on the a_ij values. On the basis of the observed trend in the values of these coefficients for CO, HCl and OH general remarks on the effects of hydrogen bonding on IR band intensities are given.     

The determination of microgram quantities of sulphide in biological materials

Several methods for the estimation of microgram quantities of sulphide in biological material and enzymatic reaction mixtures were investigated- The optimum conditions for separation of sulphide by isothermal distillation are given. The formation of méthylène blue is recommended for the spectrophotometric determination of sulphide; modifications are described to improve the reliability and sensitivity of the method.     

Dissolution Enhancement and Characterization of Nimodipine Solid Dispersions with Poloxamer 407 or PEG 6000

The solid dispersion approach is an alternative to increase drug solubility. Many carriers have been studied, but there is few information about poloxamer 407 (P407). Consequently, the objective of this study was to evaluate P407 as a carrier for nimodipine solid dispersions and to compare its solubility and dissolution rates with those from polyethylene glycol (PEG 6000). The solid dispersions were prepared by the hot melting and solvent methods and they were characterized by FTIR, DSC, solubility, and dissolution tests. The results indicated a three-fold increase in solid dispersions solubility in the presence with P407 than those prepared with PEG.     

Efficient Synthesis of Spiro[diindenopyridine-indoline]triones Catalyzed by PEG-OSO3H-H2O and [NMP]H2PO4

One-pot, three-component synthesis of spiro[diindenopyridine-indoline]triones has been reported via the reaction of 1,3-indandione, aromatic amines, and isatins with (PEG-OSO₃H) as an efficient, polymeric acid surfactant–based catalyst in water and also in presence of acidic ionic liquid [NMP]H₂PO₄, which acts both as a medium and catalyst under conventional heating and ultrasonic irradiation. The reactions were complete in short reaction times with excellent yield of products. Surfactant-based PEG-OSO₃H could be recycled and reused several times without any significant loss of activity. The compounds exhibit fluorescence in methanol with large Stokes shift.     

Sol-gel Processing of a Transparent Upconversion Luminescent Film with β-Na YF_4:Yb~(3+), Er~(3+) Microrods as Activator

β-Na YF4:Yb3+,Er3+ microrods were synthesized through hydrothermal methods. Polyethylene glycol with molecular weight of 6000 was used as surfactant. A series of transparent silica gel films with upconversion luminescence property was prepared through sol-gel method; the prepared β-Na YF4:Yb3+,Er3+ microrods were used as activator. The silica gel films show strong upconversion emission under excitation of 980-nm laser beam.