十九种长链正烷基脂肪酸的碳链骨架振动能量研究

本文通过红外光谱(FT-IR)测量数据和预测数据,计算与研究了十九种长链正烷基脂肪酸(简称脂肪酸或碳酸)的碳链骨架振动能量。结果显示出脂肪酸的碳链骨架振动能量随碳数增加呈阶梯状关系,而且脂肪酸的碳链骨架振动能量∑E出现奇偶数更迭规律。此结果可用来解释脂肪酸的熔点或熔化热呈现奇偶数更迭现象。     

2A12-T6铝合金表面双-(γ-三乙氧基硅丙基)四硫化物薄膜的特性

采用傅立叶变换红外光谱分析了2A12-T6铝合金表面自组装双-(!-三乙氧基硅丙基)四硫化物硅烷偶联剂(SCA)薄膜结构特征,并采用电化学极化曲线评价了薄膜的耐蚀性能.结果表明,铝材表面自然晾干,SCA薄膜分子之间主要通过氢键连接,腐蚀电流密度减小1个数量级以上.120℃的加热处理促进铝板表面通过SiOSi链接而形成SCA网状薄膜结构,并通过在界面上形成SiOAl界面相结构而与铝板表面牢固连接,腐蚀电流密度降低2个数量级以上.SCA乙醇溶液浸泡处理10min比浸泡2s～1min的铝板表面SCA薄膜内氢键缔合羟基要多.     

A vibrational spectroscopic study of the adsorption of 4,4′-bipyridyl by sepiolite and smectite group clay minerals from Anatolia (Turkey)

The adsorption of 4,4-bipyridyl by natural sepiolite and smectite group clay minerals (bentonite, hectorite and saponite) from Anatolia (Turkey) has been studied using vibrational spectroscopy. Investigation of Fourier-transform infrared and Fourier-transform Raman spectra of adsorbed 4,4-bipyridyl indicate the presence of chemisorbed species. However, any evidence for the generation of anionic species on the surface of the phyllosilicates has not been detected. It is proposed that the adsorbed bipyridyl molecules on sepiolite are centrosymmetric and H-bonded to the surface hydroxyls through both the nitrogen lone pairs as bidentate ligands. The adsorbed bipyridyl molecules on the smectite group clays are coordinated to exchangeable cations both directly and also indirectly through water as monodentate ligands. XRD patterns of the clays studied are also recorded.     

Thermal transformations in phosphorites

The thermal transformations in phosphorites during flash calcination were investigated by FT-IR spectroscopy, X-ray diffraction and chemical analyses. During flash calcination changes occur, both in the composition of the phosphorite and in the crystallochemistry of the fluor-carbonate-apatite (francolite). The former changes include: decomposition of a great part of the calcite in the rock and oxidation of organic matter. The latter changes include: partial removal of the structural carbonate; partial relocation of the remaining carbonate ions in the apatite structure; a new arrangement of hydroxyl groups and fluorine on the hexagonal axis; partial condensation of the orthophosphate groups and increase of crystallite sizes. Isomorphous substitution of PO ₄ ^–3 in apatite by SO ₄ ^–2 and SiO ₄ ^–4 may take place.Dedicated to Prof. Menachem Steinberg on the occasion of his 65th birthdayThe financial support from Rotem-Amfert-Negev Phosphate Co. is gratefully acknowledged. We thank Dr. B. Pregerson of the Rotem-Amfert-Negev for supplying samples     

High-temperature transformations of Cu-rich hydrotalcites

CuM(II)Al ternary hydrotalcites (M(II) = Ni, Co and Mg) with a (Cu+M(II))/Al atomic ratio of 3.0 and Cu/M(II) atomic ratio of 5.0 were synthesized by coprecipitation under low supersaturation. Powder X-ray diffraction of the as-synthesized samples showed a pattern characteristic of hydrotalcite-like (HT-like) structure (JCPDS: 41-1428). Thermal analyses of these samples showed four stages of weight loss/heat change when recorded in nitrogen. Analysis of the evolved gases characterized the nature of these transformations. The thermoanalytical effects differed significantly especially for the high-temperature transformations, when the treatment was performed in oxygen. In situ powder X-ray diffraction of the samples was carried out to elucidate the phase evolution of these compounds. Surprisingly formation of CuO was noted at temperatures around 200°C well below the destruction of the layered network. The nature of the resulting phases varied with both the nature of the co-bivalent metal ion and the heating atmosphere. FT-IR spectroscopy confirmed the retention of carbonate ions at higher temperatures (above 700°C), although the concentration of carbonate anion (most likely unidentate) varied with the calcination temperature. The crystallinity of CuO increased significantly above 600°C, probably through dissociation of copper oxycarbonate. Significant differences in the thermal transformation temperatures (for the third and the fourth transformations) of these samples containing different co-bivalent metal ions were not observed. This suggests that an association of the co-bivalent metal ions and/or trivalent metal ion in this phase is unlikely. A plausible thermal evolution scheme of these hydrotalcites is proposed.     

Investigation on the Interaction of Bendazac with β-, Hydroxypropyl-β-, and γ-, yclodextrins

The interactions of Bendazac, a topical non-steroidal anti-inflammatory drug, with-cyclodextrin, hydroxypropyl--cyclodextrin and -cyclodextrinwere investigated to evaluate possibilities to improve the drug's poor water solubilityand eventually to enhance the topical delivery of Bendazac. Phase solubility studiesdemonstrated the ability of the selected cyclodextrins to complex with Bendazac andincrease drug solubility. The amount of solubilized Bendazac increased linearly withthe addition of each cyclodextrin according toA_L type plots. ¹³C-NMR studiesshowed that the Bendazac A-ring was included in the cavity of the three cyclodextrins.The -cyclodextrin was also able to include the B-ring of Bendazac, forminga complex where one drug molecule fitted into two cyclodextrin molecules. Equimolarsolid systems of the drug with each cyclodextrin carrier were prepared using varioustechniques (physical mixing, spray-drying and freeze-drying). The results of differential scanning calorimetry and Fourier transform infrared analysis, performed on the solid systems, demonstrated that freeze-dried and spray-dried products had a high degree of amorphization and agreed with the hypothesis of the existence of drug–cyclodextrin interaction in the solid state. The cyclodextrins tested were able to improve the dissolution of Bendazac. The dissolution profile of the drug was also affected by the physico-chemical properties of each solid system, the freeze-dried products being the most rapidly dissolving forms.     

Synthesis, Characterization and Crystal Structure of （Z）-1-[2-（Triarylstannyl）vinyl]-1-indanols and Their Arylhalostannyl Derivatives

(Z)-1-[2-(Tri-o-tolylstannyl)vinyl]-1-indanol (1) and (Z)-1-[2-(tri-p-tolylstannyl)vinyl]-l-indanol (2) were synthesized by the addition reaction of 1-ethynylindanol with tri-o-tolyltin and tri-p-tolyltin hydride. The aryl groups in compound 1 and 2 were substituted by Br2 or I2 to yield monohalide derivatives (3-6). The compounds 1-6 were characterized by elemental analysis, ^1H NMR and FT-IR spectroscopy. The crystal structures of 1, 2 and 4 have been determined by single crystal X-ray diffraction analysis. The Sn atom in 1 and 2 exhibits a tetrahedral geometry distorted towards trigonal bipyramid due to a weak intramolecular interaction between Sn and the hydroxyl O atoms [0.2839(4) nm and 0.2744(5) nm], while the Sn atom in 4 adopts a trigonal bipyramidal geometry with a significant O→Sn(1) interaction [0.2552(5) nm].     

Effect of Artabotrys odoratissimus extract as an environmentally sustainable inhibitor for mild steel corrosion in 0.5 M H2SO4 media

Artabotrys odoratissimus inhibitory effect on mild steel (MS) corrosion in 0.5 M H₂SO₄ solution has been assessed utilizing mass loss, electrochemical potentiodynamic polarization, and impedance spectroscopy techniques. The Artabotrys odoratissimus plant has a wide range of bioactive compounds. Phytochemicals were tested for ethanolic Artabotrys odoratissimus leaves extract (AOLE) using the FeCl₃ test, Salkowaski's test, and others. Corrosion tests were conducted at varying inhibitor concentrations and temperatures. The inhibitory impact of AOLE on corrosion of MS was reported to improve with increasing concentration. Polarization experiments revealed that AOLE is a mixed kind of inhibitor and the inhibition efficacy (η_w) for MS is 93.27% for 1.25 g/L AOLE. For Electrochemical impedance spectroscopy (EIS), maximal inhibitory efficacy (η_w) was 91.62% due to AOLE adsorption on the MS surface. The obtained results using each methodology are highly consistent and closely resemble each other. The adsorption of AOLE molecules on an MS surface from the bulk of the solution causes the inhibitor's inhibition action, and the adsorption mechanism follows Langmuir adsorption isotherm. The computed $\Delta G_{ads}^o$ values ranged between ?32.919 and ?33.520 kJ mol^?1, implying a spontaneous and exothermic inhibitory action. The thermodynamic and activation parameters are often used to understand corrosion inhibition mechanisms. The comparison of corrosion product and pure extract FT-IR spectrum indicates the nature of AOLE adsorption on the MS surface. The surface morphology of MS samples was assessed using atomic force microscopy (AFM), scanning electron microscope (SEM), and contact angle techniques.     

Photocatalytic Reduction of NO with C2H6 on a Hollandite-Type Catalyst

The photocatalytic reduction of nitrogen monoxide (NO) with ethane on the hollandite type catalyst (K₂Ga₂Sn₆O₁₆KGSO) was investigated. Using a closed-gas circulating system equipped with a Q-MASS detector and in-situ diffuse reflectance FT-IR spectroscopy. The reactant gases of NO and ¹³C₂H₆ decreased with the increasing irradiation time. In contrast, the N₂ yield increased proportionally to the conversion of ¹³C₂H₆. Nitrogen oxides such as N₂O did not reach their detectable levels. The NO adsorbed on KGSO was found to change to its activated species by UV irradiation. The oxidized products of C₂H₆ such as CH₃CHO increased in proportion to the reaction time. The present results strongly suggest that KGSO has remarkable photocatalytic activity for the reduction of NO with C₂H₆.     

Instrumental barriers in biological Fourier transform infrared spectroscopy

Biological applications of infrared spectroscopy have pressed for ever greater instrumental capabilities in terms of spectral sensitivity and quantitative exactness. Improved instrumentation has provided measurement of many vibrational modes in biological samples that previously were lost in noise. With highly optimized sampling conditions, useful measurements have been made with a peak-to-peak noise level less than 5 microabsorbance (5×10^–6 absorbance), at 0.5 cm^–1 resolution. However, optical and instrumental instabilities often result in sine waves that are not totally removed by the ratio of sample to reference. These often limit effective spectral sensitivity to 50 or 100 microabsorbance, peak-to-peak, and constitute a non-random noise. Non-atmospheric absorptions, especially one at 1959 cm^–1 with 0.8 cm^–1 band width (FWHM) are reported. The latter is due to a trace impurity in the KBr beam splitter substrate and compensator plate. Improvements in instrumentation and sampling conditions are expected to yield measurements of absorption bands as small as 50 microabsorbance with excellent signal/noise.