Modified data handling for rapid low-field nuclear magnetic resonance characterization of lyotropic liquid crystal composites

A refined nuclear magnetic resonance (NMR) technique was developed to determine the relative volumetric proportions of various phases present in lyotropic liquid crystal (LLC) composites such as soap/detergent bars. Conventionally, the FID (free induction decay, referred to hereafter as Method 1) technique is used for analysis of these systems. This technique is suitable only for composites containing a high concentration of solids and liquid crystals. Method 1 gives erroneous results for composites with a high proportion (>10%) of isotropic liquid phase (L ₁). The procedure currently practiced (Method 2) for analyzing systems containing >10% L ₁ entails a considerable amount of experimental and analysis time and involves subjectivity in data analysis. Typically, the phase characterization of the composite using conventional low-field NMR techniques takes more than 1 h. Furthermore, the hardware and data acquisition features of currently available conventional low-field NMR spectrometers are inadequate for accurate estimation of relative phase volumes in LLC composites. We developed a modified data-handling technique (FID—Carr-Purcell-Meiboom-Gill technique, or FIDCPMG technique) which enabled rapid phase characterization of LLC composites and minimized subjectivity while analyzing the data. The standard design of a conventional low-field NMR spectrometer was upgraded by incorporating a high-power transmitter and a fast digitizer. The phase composition of four model LLC composites (with L ₁ percentages varying from 7 to 90%) was determined using FIDCPMG technique and was compared with results from conventional techniques. Phase composition of the LLC composite could be determined in less than 5 min.     

Hydration effects of Al2(MoO4)3 and AlPO4 phases in hydrotreating catalysts studied by solid state nuclear magnetic resonance spectroscopy

Solid state nuclear magnetic resonance spectroscopy of²⁷Al,³¹P, and⁹⁵Mo nuclei was used to investigate species on a NiPMo/Al₂O₃ hydrotreating catalyst calcined at 750 °C before and after rehydration. The Al₂(MoO₄)₃ phase disappeared after rehydration in 100% relative humidity at room temperature. However, almost none of the observed crystalline AlPO₄ reacted with adsorbed water. The results show that the Al₂(MoO₄)₃ phase on an alumina surface reacts easily with moisture unlike Al₂(MoO₄)₃ in the bulk phase. It also suggests that the crystalline AlPO₄ phase is formed under the Al₂(MoO₄)₃ phase or that both species are formed as neighboring islands on the surface of the alumina but have different reactivities toward moisture.     

Characterization of fish oil-in-water emulsions using light-scattering,nuclear magnetic resonance,and gas chromatography-headspace analyses

The effect of the molecular environment on the physical and oxidative properties of homogenized or microfluidized fish oil-in-water emulsions (5% w/w tuna oil in pH 7 phosphate buffer) stabilized by whey protein isolate (WPI, 1 or 5% w/w) or lecithin (2.5% w/w) was examined. Laser light-scattering measurements showed that WPI-stabilized emulsions had smaller particle sizes than lecithin-stabilized emulsions, and that higher pressures reduced the particle size. WPI afforded more protection against oil oxidation than did lecithin, as evidenced by the lower headspace propanal of emulsions as measured by GC-headspace analysis, despite the larger interface in WPI-stabilized emulsions. Reducing the concentration of WPI in emulsions from 5 to 1% decreased the oxidative stability of WPI-stabilized emulsions. The ¹H NMR transverse relaxation times (T ₂) of FA chains in emulsion droplets stabilized by the same surfactants made by homogenization or microfluidization were different and not always related to particle size. The higher mobility (i.e., longer T ₂) of the unsaturated parts of the FA chains within an oil droplet, compared with the saturated parts, suggests that the unsaturated components tended to stay in the core of the oil droplets. This experimental result supports the hypothesis reported in other literature that the more unsaturated FA are buried in the oil core of oil-in-water emulsions. The lack of a universal correlation between particle size and oxidation suggests that the mobility of particles in an emulsion has an influence on the rate of oxidation.     

Quantitative analysis of partial acylglycerols and free fatty acids in palm oil by 13C nuclear magnetic resonance spectroscopy

The chemical shifts, spin-lattice relaxation times (T ₁), and one-bond C−H coupling constants of the glycerol carbons of mono-, di-, and triacylglycerols in CDCI₃ solution are presented and discussed. The glycerol carbons have low T ₁ values (<1.0 s) and full nuclear Overhauser effect and also exhibit broader linewidths than the aliphatic carbons, suggesting that the glycerol carbons are at or near the T ₁ minimum for the dipole-dipole relaxation mechanism. Therefore, for quantitative measurement of the composition of partial acylglycerols (relative to the triacylglycerols) in palm oil, the nuclear magnetic resonance (NMR) spectrum of the β-carbons, which lie exclusively in the region δ68.3–72.1 ppm, should preferably be acquired at medium or low magnetic fields and at an elevated temperature in order to ensure that the condition for extremely narrow spectral lines is satisfied. The chemical shifts and spinlattice relaxation times of the aliphatic C-2 and C-3 carbons and of the carbonyl carbons (C-1) of acyl groups present in palm oil are also presented and discussed. The presence of free fatty acid in the palm oil is easily detected and quantified in the spectrum of the aliphatic carbons. The presence of partial acylglycerols in palm oil can also be detected and/or quantified in the NMR spectra of the C-2 and the carbonyl carbons. The quantitative analysis of the glycerol carbons of a known mixture of acylglycerols obtained by using this method is presented.     

Identification of cyclopentenyl fatty acids by 1H and 13C nuclear magnetic resonance

Gorlic, chaulmoogric and hydnocarpic fatty acids, specific to the seed oil of the genus Hydnocarpus sp. (Flacourtiaceae), are determined only with difficulty by gas chromatography. These fatty acids were isolated in their methyl ester form by a combination of different chromatographic techniques (thin-layer chromatography/Ag⁺ and high-pressure liquid chromatography). The proton and carbon nuclear magnetic resonance analysis of these fatty acid methyl esters showed some characteristic signals of the cyclopentenyl ring. The presence of these signals in the proton and/or carbon nuclear magnetic resonance spectrum of an oil thus will allow us to confirm the presence of these cyclopentenyl fatty acids in lipids.     

Rapid determination of iodine value by 1H nuclear magnetic resonance spectroscopy

High-resolution ¹H nuclear magnetic resonance (¹H NMR) has been found to be an effective tool for the direct, rapid, and automated determination of the iodine value (IV) of vegetable oils, including hydrogenated oils (IV=45.9–140.2). The total time required to obtain the ¹H NMR data is about 3 min per sample. The IV is calculated from the number of double-bonded protons and the average molecular weight derived directly from the spectrum. The average of olefinic protons and allylic plus divinyl protons area was used to calculate the absolute number of double-bonded protons. The ¹H NMR results were compared with those obtained by the traditional Wijs-cyclohexane methods. The correlation coefficient between traditional IV and the novel ¹H NMR method was r ²=0.9994 for the regression equation Y=0.9885X + 2.8084, where X was the result given by the traditional method. With the proposed regression equation, IV calculated by the ¹H NMR method was within an error of ± 1 unit of the result obtained by the traditional method. The proposed method is practically viable if one can afford to have the NMR system.     

Characterization of the micellar structure of a barium nonylphenolate/Barium carbonate complex by nuclear magnetic resonance spectroscopy

The micellar structure of a barium nonylphenolate/barium carbonate complex was characterized by ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy. Several NMR techniques, including measurement of spin-lattice relaxation time, chemical shift variation, and line width of the ¹H NMR signal and solid-state ¹³C NMR data, were used in this study. NMR results indicate that the prepared barium nonylphenolate and barium carbonate complex formed a micelle structure with the oxygen atom of the nonylphenolate ring oriented toward the solid-state center core of barium carbonate while the highly branched aliphatic chain pointed outward to the hydrocarbon solvent.     

Measurement of water content and moisture distribution in sludge by 1H nuclear magnetic resonance spectroscopy

Moisture distribution in sludge is essential for the examination of dewatering problems; however, sufficiently rapid and accurate methods of sludge moisture measurement are currently lacking. Hence, this study investigated a low-field ¹H nuclear magnetic resonance (NMR) method for measuring water content and moisture distribution in sludge. Moisture content measured by NMR was closely correlated with the thermal drying method (R² = 0.999). The loss of mechanical bound water from sludge was the primary cause of the decrease in water content from 96 to 37% during thermal drying at 40°C. NMR is more accurate, rapid, and nondestructive than other water distribution measurement methods.     

Two-dimensional correlation relaxometry studies of cement pastes performed using a new one-sided NMR magnet

We present preliminary results of the first NMR T₁-T₂ two-dimensional relaxation correlation experiments performed using a one-sided NMR system in cement based materials. Two-dimensional correlation relaxometry has itself only recently been demonstrated in cement paste where it proved to be a particularly sensitive probe of pore-water dynamics providing direct information on exchange of water between the gel and capillary pore networks. Further to this we have observed differences in the structural development of a selection of cement pastes throughout the early stages of hydration and verified the theoretical frequency dependence of the ratio T₁ / T₂. When coupled with instrumentation developments in one-sided NMR magnets the way is opened to detailed, spatially resolved studies of the development of hydration and porosity in the surface layers (top 50 mm) of cementitious materials. A new magnet, suitable for such applications, is discussed.     

Off-line coupling of high-performance liquid chromatography and 1H nuclear magnetic resonance for the identification of filbertone in hazelnut oil

A new procedure is presented for off-line coupling of high-performance liquid chromatography and proton nuclear magnetic resonance spectroscopy (¹H NMR) in hazelnut oil analysis. The optimization of some parameters affecting both the liquid chromatography preseparation step and the effective multiple-solvent suppression required for the NMR study enabled us to determine the presence in a hazelnut oil of (E)-5-methyl-hept-2-en-4-one (filbertone), a marker previously proposed to detect the adulteration of olive oil with hazelnut oil. The described procedure requires the filtration of the oil prior to its introduction into the chromatographic system and combines the advantages of providing sufficient sensitivity and selectivity with simple methodology and reduced sample handling.     

Isookanin Inhibits PGE2-Mediated Angiogenesis by Inducing Cell Arrest through Inhibiting the Phosphorylation of ERK1/2 and CREB in HMEC-1 Cells

Inflammation is increasingly recognized as a critical mediator of angiogenesis, and unregulated angiogenic responses often involve human diseases. The importance of regulating angiogenesis in inflammatory diseases has been demonstrated through some successful cases of anti-angiogenesis therapies in related diseases, including arthritis, but it has been reported that some synthetic types of antiangiogenic drugs have potential side effects. In recent years, the importance of finding alternative strategies for regulating angiogenesis has begun to attract the attention of researchers. Therefore, identification of natural ingredients used to prevent or treat angiogenesis-related diseases will play a greater role. Isookanin is a phenolic flavonoid presented in Bidens extract, and it has been reported that isookanin possesses some biological properties, including antioxidative and anti-inflammatory effects, anti-diabetic properties, and an ability to inhibit α-amylase. However, its antiangiogenic effects and mechanism thereof have not been studied yet. In this study, our results indicate that isookanin has an effective inhibitory effect on the angiogenic properties of microvascular endothelial cells. Isookanin shows inhibitory effects in multiple stages of PGE₂-induced angiogenesis, including the growth, proliferation, migration, and tube formation of microvascular endothelial cells. In addition, isookanin induces cell cycle arrest in S phase, which is also the reason for subsequent inhibition of cell proliferation. The mechanism of inhibiting angiogenesis by isookanin is related to the inhibition of PGE₂-mediated ERK1/2 and CREB phosphorylation. These findings make isookanin a potential candidate for the treatment of angiogenesis-related diseases.     

Copolymerization of norbornene with ethylene: A high-resolution liquid NMR, DSC and solid state NMR study

In this paper, we report the monomer reactivity on the copolymerization of norbornene and ethylene. The reactivity ratios for ethylene (M₁) and norbornene (M₂) are 18.5 and 0.035, respectively. Different copolymerization conditions can produce COC with different microstructures. A ¹³C NMR shift assignment in pentad sequences in copolymers has been obtained. More isolated polynorbornene or a micro-block length can be obtained using a low Zr/Al catalyst/co-catalyst ratio and at a lower NB/ethylene feed ratio. The T_1p ^C decay curve shows two component decays in all resonance peaks. These two component decays come from different norbornene microstructures, while the block and alternative have similar T_1p ^C values.     

Determination of Cis- and Trans-18:1 fatty acid isomers in hydrogenated vegetable oils by high-resolution carbon nuclear magnetic resonance

Carbon nuclear magnetic resonance (¹³C NMR) methods for determining the composition of cis-/trans- and positional isomers in hydrogenated vegetable oils were developed to reduce analytical time. By selecting appropriate olefinic carbon peaks and by measuring individual peak areas subsequent to the identification of isomeric peaks on the NMR spectrum, compositional results of the isomers coincided well with those obtained by conventional gas chromatography (GC). Therefore, it is highly beneficial to choose the ¹³C NMR method when analysis time is limited. Though the proposed ¹³C NMR method is promising, further development is needed. For the time being, combination with the traditional GC method is still encouraged for precise compositional analysis of cis-/trans- and positional isomers.     

Synthesis of LiNi1/3Co1/3Mn1/3O2 cathode materials by using a supercritical water method in a batch reactor

LiNi_1/3Co_1/3Mn_1/3O₂ and LiCoO₂ cathode materials were synthesized by using a supercritical water (SCW) method with a metal salt solution in a batch reactor. Stoichiometric LiNi_1/3Co_1/3Mn_1/3O₂ was successfully synthesized in a 10-min reaction without calcination, while overlithiated LiCoO₂ (Li_1.15CoO₂) was synthesized using the batch SCW method. The physical properties and electrochemical performances of LiNi_1/3Co_1/3Mn_1/3O₂ were compared to those of Li_1.15CoO₂ by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and charge/discharge cycling tests. The XRD pattern of LiNi_1/3Co_1/3Mn_1/3O₂ was found to be similar to that of Li_1.15CoO₂, showing clear splitting of the (0 0 6)/(1 0 2) and (1 0 8)/(1 1 0) peak pairs as particular characteristics of the layered structure. In addition, both cathode powders showed good crystallinity and phase purity, even though a short reaction time without calcination was applied to the SCW method. The initial specific discharge capacities of the Li_1.15CoO₂ and LiNi_1/3Co_1/3Mn_1/3O₂ powders at a current density of 0.24 mA/cm² in 2.5-4.5 V were 149 and 180 mAh/g, and their irreversible capacity loss was 20 and 17 mAh/g, respectively. The discharge capacities of the Li_1.15CoO₂ and LiNi_1/3Co_1/3Mn_1/3O₂ powders decreased with cycling and remained at 108 and 154 mAh/g after 30 cycles, which are 79% and 89% of the initial capacities. Compared to the overlithiated LiCoO₂ cathode powders, the LiNi_1/3Co_1/3Mn_1/3O₂ cathode powders synthesized by SCW method had better electrochemical performances.     

Positional distribution of ω3 Fatty acids in marine lipid triacylglycerols by high-resolution13C nuclear magnetic resonance spectroscopy

The positional distribution [α(1,3)-acyl and ß(2)-acyl] of ω3 fatty acids [18:4(n-3), 20:4(n-3), 20:5(n-3), 22:5(n-3) and 22:6(n-3)] in depot fat of Atlantic salmon (Salmo salar), harp seal oil and cod liver oil triacylglycerols has been examined by¹³C nuclear magnetic resonance (NMR) spectroscopy. The positional distribution data can be defined from the spectrum of the carbonyl (C1 carbon) and the methylene (C2 and glyceryl carbon) regions. In depot fat of Atlantic salmon and cod liver oil, docosahexaenoic acid (DHA) was concentrated in the ß-position of the triacylglycerides with 72.6 and 74.4%, respectively. Only 3.2% of DHA and 4.6% of eicosapentaenoic acid (EPA) were esterified to the ß-position of the triacylglycerides in harp seal oil. EPA is nearly randomly distributed in cod liver oil and muscle lipids of Atlantic salmon, with 37.8 and 39.7%, respectively, in the ß-position. In general, the¹³C NMR-derived data were in accordance with corresponding data reported in the literature obtained by conventional techniques.     

Structural and electrochemical behaviors of metastable Li2/3[Ni1/3Mn2/3]O2 modified by metal element substitution

Layered metastable lithium manganese oxides, Li_2/3[Ni_1/3−xMn_2/3−yM_x+y]O₂ (x = y = 1/36 for M = Al, Co, and Fe and x = 2/36, y = 0 for M = Mg) were prepared by the ion exchange of Li for Na in P2-Na_2/3[Ni_1/3−xMn_2/3−yM_x+y]O₂ precursors. The Al and Co doping produced the T^#2 structure with the space group Cmca. On the other hand, the Fe and Mg doped samples had the O6 structure with space group R-3m. Electron diffraction revealed the 1:2 type ordering within the Ni_1/3−xMn_2/3−yM_x+yO₂ slab. It was found that the stacking sequence and electrochemical performance of the Li cells containing T^#2-Li_2/3[Ni_1/3Mn_2/3]O₂ were affected by the doping with small amounts of Al, Co, Fe, and Mg. The discharge capacity of the Al doped sample was around 200 mAh g⁻¹ in the voltage range between 2.0 and 4.7 V at the current density of 14.4 mA g⁻¹ along with a good capacity retention. Moreover, for the Al and Co doped and undoped oxides, the irreversible phase transition of the T^#2 into the O2 structure was observed during the initial lithium deintercalation.     

Partial oxidation of methane catalyzed by YBa2Cu3Ox in a solid state electrochemical reactor

The catalytic oxidation of methane was studied between 840 and 1110 K on a YBa₂Cu₃O* mixed-conducting electrode deposited on an yttria stabilized zirconia solid electrolyte. The lattice oxygen supplied electrochermically to the catalyst surface actively participated in the oxidation reaction, with CO as the major product, and CO₂, CH₃OH and HCHO as the minor products. The reaction rate was found to be of first order with respect to methane. The rate constant depended strongly on the electrochemically imposed bias. Under DC bias condition, the reaction rate was enhanced by as much as two orders of magnitude over that observed under open-circuit conditions. An Eley-Rideal mechanism for the interaction of CH₄ with surface oxygen is proposed as the rate-determining step.     

DUSP-1 Induced by PGE2 and PGE1 Attenuates IL-1β-Activated MAPK Signaling,Leading to Suppression of NGF Expression in Human Intervertebral Disc Cells

The molecular mechanism of discogenic low back pain (LBP) involves nonphysiological nerve invasion into a degenerated intervertebral disc (IVD), induced by nerve growth factor (NGF). Selective cyclooxygenase (COX)-2 inhibitors are mainly used in the treatment of LBP, and act by suppressing the inflammatory mediator prostaglandin E₂ (PGE₂), which is induced by inflammatory stimuli, such as interleukin-1β (IL-1β). However, in our previous in vitro study using cultured human IVD cells, we demonstrated that the induction of NGF by IL-1β is augmented by a selective COX-2 inhibitor, and that PGE₂ and PGE₁ suppress NGF expression. Therefore, in this study, to elucidate the mechanism of NGF suppression by PGE₂ and PGE₁, we focused on mitogen-activated protein kinases (MAPKs) and its phosphatase, dual-specificity phosphatase (DUSP)-1. IL-1β-induced NGF expression was altered in human IVD cells by MAPK pathway inhibitors. PGE₂ and PGE₁ enhanced IL-1β-induced DUSP-1 expression, and suppressed the phosphorylation of MAPKs in human IVD cells. In DUSP-1 knockdown cells established using small interfering RNA, IL-1β-induced phosphorylation of MAPKs was enhanced and prolonged, and NGF expression was significantly enhanced. These results suggest that PGE₂ and PGE₁ suppress IL-1β-induced NGF expression by suppression of the MAPK signaling pathway, accompanied by increased DUSP-1 expression.     

Monitoring the bactericidal effect of UV-A photocatalysis: A first approach through 1D and 2D protein electrophoresis

The bactericidal effect of UV-A photocatalysis is studied through the 1D and 2D protein electrophoresis biochemical approach over model and bacterial proteins, which shows that a majority of proteins are heavily and non-specifically damaged. This suggests that the emergence of resistance to this treatment should be almost impossible.     

Separation of CO2 by 2-amino-2-methyl-1-propanol aqueous solution in microporous hydrophobie hollow fiber contained liquid membrane

The absorption of CO₂ from a mixture of CO₂/N₂ gas was carried out using a flat-stirred vessel and the polytetrafluoroethylene hollow fiber contained aqueous 2-amino-2-methyl-1-propanol (AMP) solution. The reaction of CO₂ with AMP was confirmed to be a second order reversible reaction with fast-reaction region. The mass transfer resistance in the membrane side obtained from the comparison of the measured absorption rates of CO₂ in a hollow fiber contained liquid membrane with a flat-stirred vessel corresponded to about 90% of overall-mass-transfer resistance. The mass transfer coefficient of hollow fiber phase could be evaluated, which was independent of CO₂ loading.