Recurrent equations of physicochemical constants for homologs substantiated with numerical sequences

The applicability of the unified first order recurrent equations A(n + 1) = aA(n) + b to the approximation of the physicochemical constants of various organic compounds (not only members of homologous series), previously found for normal boiling points, was extended to the dielectric constant (ε). This tendency is equivalent to the general procedure for calculating the ε of any compound from the data for preceding homologs with an accuracy comparable to the average interlaboratory reproducibility of the results of ε measurements. To substantiate this universal character of recurrent relations we consider the analogy between the constants of successive homologs and the recursive numerical sequences (Fibonacci and Padovan sequences versus Lucas and Perrin sequences, respectively).     

Metabolic N-Dealkylation and N-Oxidation as Elucidators of the Role of Alkylamino Moieties in Drugs Acting at Various Receptors

Metabolic reactions that occur at alkylamino moieties may provide insight into the roles of these moieties when they are parts of drug molecules that act at different receptors. N-dealkylation of N,N-dialkylamino moieties has been associated with retaining, attenuation or loss of pharmacologic activities of metabolites compared to their parent drugs. Further, N-dealkylation has resulted in clinically used drugs, activation of prodrugs, change of receptor selectivity, and providing potential for developing fully-fledged drugs. While both secondary and tertiary alkylamino moieties (open chain aliphatic or heterocyclic) are metabolized by CYP450 isozymes oxidative N-dealkylation, only tertiary alkylamino moieties are subject to metabolic N-oxidation by Flavin-containing monooxygenase (FMO) to give N-oxide products. In this review, two aspects will be examined after surveying the metabolism of representative alkylamino-moieties-containing drugs that act at various receptors (i) the pharmacologic activities and relevant physicochemical properties (basicity and polarity) of the metabolites with respect to their parent drugs and (ii) the role of alkylamino moieties on the molecular docking of drugs in receptors. Such information is illuminative in structure-based drug design considering that fully-fledged metabolite drugs and metabolite prodrugs have been, respectively, developed from N-desalkyl and N-oxide metabolites.     

The Physicochemical Characteristics of Gelam Honey and Its Outcome on the Female Reproductive Tissue of Sprague–Dawley Rats: A Preliminary Study

Gelam honey (GH) is a prized natural product synthesized from the nectar of flowers from Gelam trees (Melaleuca sp.). Gelam is an evergreen tree species that grows in tropical regions such as Malaysia. GH is a multifloral honey with proven antioxidant and anti-inflammatory properties. However, the beneficial effect of GH on female reproductive tissue has yet to be substantiated. Herein, we investigated the effects of GH administration on the uterine and vaginal epithelial thickness of sexually mature Sprague–Dawley rats. Epithelia thickness could be an indicator of an atrophy manifesting as a symptom of a cardio syndrome. Rats were given oral doses of GH in four groups for 14 days; the lowest dose was 0.2 g GH/kg body weight (bw) rat/day and the highest dose was 8 g GH/kg bw rat/day. The physicochemical characteristics of GH were assessed through hydroxymethylfurfural and moisture content determination and sugar identification. GH attenuated the atrophy of the uterine and vaginal epithelia and increased the thickness of the endometrial stroma and endometrial surface endothelial layer. However, the dissonance observed in the effect of GH administration on the vaginal epithelium requires further investigation. Nevertheless, GH may have a strong potential in attenuating uterine and vaginal atrophies.     

脱灰预处理对水稻秸秆物化性/水蒸气气化反应特性的影响

在固定床反应器中研究了水洗、不同浓度酸洗预处理对水稻秸秆物化性/水蒸气气化反应特性的影响。结果表明,水洗处理后稻秆中的钾、钠脱除率分别为90.5%和82.1%,酸洗处理后稻秆中的钾脱除率达到99.2%,而钠脱除率随酸种类略有差异,在84.6%~92.3%;酸洗并未改变稻秆中主要组分含量,但破坏了稻秆微观物理结构。比较不同浓度酸洗后稻秆的孔容、孔径分布、BET比表面积发现,各指标的排列顺序均为水洗稻秆>3%硫酸洗后稻秆>原稻秆>7%硫酸洗后稻秆>10%硫酸洗后稻秆;各种预处理酸的浓度均为3%时,硫酸洗后稻秆的孔容、孔径分布、BET比表面积最大,而磷酸洗后稻秆各指标则最小。水蒸气气化结果表明,钾、钠及丰富的孔径结构均能促进H₂的生成,且钾、钠对气化过程的作用明显强于孔径结构对气化过程的影响。水洗稻秆气化产气中H₂、CO₂的瞬时释放浓度高于酸洗稻秆;CO、CH₄则相反。4种酸的浓度为3%时,稻秆气化中H₂、CO₂瞬时释放浓度与稻秆孔径分布呈正相关性;CO、CH₄瞬时释放浓度则与稻秆孔径分布呈负相关性。4种酸浓度为3%时,孔径越丰富,气化速率越快。脱灰预处理虽降低了稻秆气化氢气产率,但提高了气化气体热值。     

基于理化指标及主成分分析的葵花籽油品质综合评价指标的建立

研究了105℃和180℃氧化条件下葵花籽油理化指标(过氧化值、共轭二、三烯、茴香胺值、酸价、碘值和极性化合物)的变化规律,就理化指标对油脂总体品质变化的贡献度进行了主成分分析,建立了可有效表征葵花籽油在相应条件下品质变化的综合评价指标。结果表明:随着氧化时间的延长、温度的升高,共轭二、三烯、茴香胺值、酸价和极性化合物的升高趋于显著(P≤0.05),而碘值则均呈下降趋势;通过对各理化指标的总体变化率以及与油脂不饱和度和常用理化指标的相关性分析,发现过氧化值、共轭二烯、茴香胺值(105℃)或共轭二烯、茴香胺值、极性化合物(180℃)可有效表征葵花籽油的品质变化;成功建立了评判葵花籽油品质变化的综合指标,并确定其临界值分别为-0.189(105℃)和0.727(180℃);此外,可通过对共轭二烯和茴香胺值的主成分分析有效区分在105℃或180℃下氧化葵花籽油的品质变化。     

含脱氢松香酸骨架的吖啶染料的合成及其理化性质研究

以脱氢松香酸为原料,经甲酯化、硝化、还原、关环和水解等多步合成了三个松香基吖啶酮化合物7a～7c.通过1HNMR,13C NMR,MS和IR等表征手段对产物结构进行了表征,并采用紫外-可见分光光度法对化介物的理化性质进行研究.     

Physicochemical,structural, and digestive properties of pea starch obtained via ultrasonic-assisted alkali extraction

As a new and clean extraction technology, ultrasonic extraction has been demonstrated with great potential in the preparation of modified starch. In order to increase its added value, it is necessary to modify pea starch to enlarge its application. In this study, the efficiency of combining ultrasonic with alkali in the extraction of pea starch was evaluated and compared to conventional alkali extraction. Ultrasonic-assisted alkali extraction conditions were optimized using single-factor experiments and response surface methodology. The results revealed that maximum yield of pea starch (54.43 %) was achieved using ultrasound-assisted alkali extraction under the following conditions: sodium hydroxide solution with a concentration of 0.33 %, solid/alkali solution ratio of 1:6 (w/v), ultrasonic power of 240 W, temperature of 42 °C, and extraction time of 22 min. The ultrasound-assisted alkali extraction yielded 13.72 % greater pea starch than conventional alkali extraction. On the other hand, morphological, structural, and physicochemical properties of the obtained starch isolates were evaluated. The ultrasound-assisted alkali extraction resulted in pea starch with greater amylose content, water-solubility, swelling power, and viscosity compared with conventional alkali extraction. Furthermore, ultrasonication influenced the morphological properties of pea starch granules, while the molecular structure and crystal type were not affected. Moreover, the ultrasonic-assisted extraction produced starch with a slightly greater resistant starch content. Therefore, ultrasonic-assisted extraction can be suggested as a potential method for extracting pea starch with improved functional properties.     

Some novel neighborhood degree sum-based versus degree-based topological indices in QSPR analysis of alkanes from n-butane to nonanes

The topological indices are reported to be very useful in various QSPR studies as these indices can be utilized as a tool to predict the physicochemical properties of a diverse set of chemical compounds. The objective of this communication is twofold. First, to introduce some neighborhood degree sum-based topological indices and perform a comparative QSPR analysis of the indices with their corresponding degree-based topological indices to analyze the usefulness of the new indices. Second, to investigate isomer discrimination ability of the newly defined indices on the basis of degeneracy test. Neighborhood degree sum-based topological indices not only consider the degree of each atom in the molecule but also the degrees of its neighboring atoms. Moreover, these indices are expected to provide information about how connected and dense the neighborhoods of atoms are within the molecule. In this study, we observe that the proposed neighborhood degree sum-based topological indices exhibit better correlation with some physicochemical properties of Octane Isomers and 66 alkanes as compared to their corresponding degree-based topological indices. Also, the supremacy in terms of sensitivity of the neighbourhood degree sum-based topological indices as compared to the classical degree-based ones is established.     

Chemometrics in fuel science: demonstration of the feasibility of chemometrics analyses applied to physicochemical parameters to screen solvent tracers in Brazilian commercial gasoline

Samples of commercial gasoline, from the National Program of Fuel Quality Monitoring of the National Petroleum Agency, were collected from gas stations located in the Midwestern state of Sao Paulo, Brazil, and analyzed by several physicochemical standard methods established by ANP Resolution no. 309. Also, important information related to tampering was analyzed with the marker solvent. Statistical analysis and exploratory chemometric were employed to discriminate the presence of markers of solvents in commercial gasoline. The results showed that statistical and chemometric parameters such as atmospheric distillation temperatures T10 and T90, RON, benzene and saturated and aromatic hydrocarbons satisfactorily describe the presence of marker solvent, usually with a probability exceeding 70%. Furthermore, after optimizing the SIMCA algorithm, sensitivity in the training set with cross‐validation leave‐one‐out (83.8%) and the set of prediction (77.1%) were revealed. The proposed method will become indispensable and recommended for discriminating samples of fuels for commercial applications in routine monitoring programs and quality control. Copyright © 2011 John Wiley & Sons, Ltd.     

功能化离子液体的催化作用及其应用

功能化离子液体是将功能团弓l入到离子液体的阳离子或阴离子上,从而赋予离子液体某种特殊性质．将具有催化活性的基团弓I入到离子液体的阳离子或阴离子上所得到的功能化离子液体,是一类新型的催化材料．除了具有优异的催化性能,其特殊的物理化学性质很容易实现产物与催化剂的分离,正在许多重要催化过程中发挥作用．本文主要介绍近年来我们关于功能化离子液体的制备、性质及其在催化反应中的应用等研究,同时指出了目前存在的问题,并对今后发展趋势进行了展望．