Analytical FT‐Raman spectroscopy to chemotype Leptospermum scoparium and generate predictive models for screening for dihydroxyacetone levels in floral nectar

Leptospermum scoparium (Mānuka) is the source of nectar for Unique Mānuka Factor (UMF) honey. The chemical component of interest to this study is dihydroxyacetone (DHA). DHA is the precursor for the chemical methylglyoxyl which is the main chemical responsible for the UMF activity in Manuka honey. Screening commercially bred plants for increased DHA synthesis in L. scoparium is a critical factor in growing the Manuka Honey industry in New Zealand. FT‐Raman spectroscopy, in combination with principal component analysis and partial least squares regression analysis, was investigated as an analytical tool for building a screening model for DHA in the nectar of L. scoparium. Leaf samples of seven cultivars of the species L. scoparium were collected in an attempt to correlate metabolic factors in the plant with DHA synthesis in the nectar. Leaf material was analysed using Fourier transform‐raman spectroscopy (FT‐Raman). The DHA levels in nectar samples of the same cultivars were measured using standard LC‐MS methods. This study showed that the application of multivariate analysis of FT‐Raman spectra from leaf material is a useful tool to screen for DHA potential in L. scoparium. The PLS regression shows that we can screen for DHA concentrations in the range of 3300–7600 mg/kg plus or minus 20% standard error and can distinguish low medium and high DHA synthesis in the group of plants studied. The model for predicting DHA concentrations is influenced by a significant contribution from the spectral variance due to beta‐carotene and other highly scattering compounds that are not directly correlated with UMF. Copyright © 2014 John Wiley & Sons, Ltd.     

Influence of the ordered structure of short-chain polymer molecule all-trans-β-carotene on Raman scattering cross section in liquid

We measured the resonant Raman spectra of all-trans-β-carotene in solvents with different densities and concentrations at different temperatures.The results demonstrated that the Raman scattering cross section(RSCS) of short-chain polymer all-trans-β-carotene is extremely high in liquid.Resonance and strong coherent weakly damped CC bond vibrating properties play important roles under these conditions.Coherent weakly damped CC bond vibration strength is associated with molecular ordered structure.All-trans-β-carotene has highly ordered structure and strong coherent weakly damped CC bond vibrating properties,which lead to large RSCS in the solvent with large density and low concentration at low temperature.     

Reflections on Ernest Roy Davidson: the UW years 1962–1984

In the following research acetylation as an unexplored factor in the anomeric effect in carbohydrate chemistry has been examined. Crystallographic data for methyl glycosides and their acetates have been compared and discussed. Some of the methyl glycosides form hydrogen bonding with the participation of acetal oxygen atoms. This seems to have the most significant influence on the structural diagnostic parameters for anomeric effect.

Abbreviations: Me-α-Glc: methyl α-D-glucopyranoside; Me-β-Glc: methyl β-D-glucopyranoside; Me-α-Gal: methyl α-D-galactopyranoside; Me-β-Gal: methyl β-D-galactopyranoside; Me-α-Man: methyl α-D-mannopyranoside; Me-β-Man: methyl β-D-mannopyranoside; Ac-Me-α-Glc: methyl 2,3,4,6-tetra-O-acetyl-α-D-glucopyranoside; Ac-Me-β-Glc: methyl 2,3,4,6-tetra-O-acetyl-β-D-glucopyranoside; Ac-Me-α-Gal: methyl 2,3,4,6-tetra-O-acetyl-α-D-galactopyranoside; Ac-Me-β-Gal: methyl 2,3,4,6-tetra-O-acetyl-β-D-galactopyranoside; Ac-Me-α-Man: methyl 2,3,4,6-tetra-O-acetyl-α-D-mannopyranoside; Ac-Me-β-Man: methyl 2,3,4,6-tetra-O-acetyl-β-D-mannopyranoside; GIPAW (Gauge Including Projector Augmented Waves) calculations: a DFT based method used for calculating nuclear magnetic resonance parameters; CP/MAS NMR: cross-polarisation (CP) magic angle spinning (MAS) NMR spectroscopy; δ_ss: chemical shift in ¹³C CP/MAS NMR spectrum; δ_t: theoretical chemical shift: as derived from GIPAW DFT; dis: distorted multiplet in ¹H NMR spectrum.     

Differentiation of Isomeric Polyphenolic Glycosides That Possess Regioisomeric Acylated Monosaccharide Residues by Electrospray Ionization–Tandem Mass Spectrometry

Isomeric polyphenolic glycosides that possess regioisomeric O-acylated saccharide residues can be found in many medicinal plants and their preparations as well as some synthetic intermediates. The need for a pure and sufficient quantity of compounds for nuclear magnetic resonance measurements calls for a microanalytical method for their rapid differ entiation. In the current investigation, an electrospray ionization–tandem mass spectrometric method was developed for rapid differentiation of two pairs of regioisomeric acylated monosaccharides, quercetin-3-O-(3″-O-galloyl)-α-L-rhamnopyranoside and quercetin-3-O-(2″-O-galloyl)-α-L-rhamnopyranoside as well as quercetin-3-O-(3″-O-galloyl)-β-D-glucopyranoside and quercetin-3-O-(2″-O-galloyl)-β-D-glucopyranoside; the mechanisms governing their similar or differential fragmentations are also discussed. The work may facilitate the structural determination of these regioisomers and their analogs in pure form or in complex matrix.     

Orientational order and distribution function in nematic 1-(4-trans hexylcyclohexyl)-4-[(2-4-isothiocyanato phenyl)ethyl] benzene

The refractive indices (n _e,?n _o) and density have been measured as a function of temperature in the liquid-crystalline and liquid phases of nematic 1-(4-trans hexylcyclohexyl)-4-[(2-4-isothiocyanato phenyl)ethyl] benzene. The molecular polarizability and orientational order parameter have been computed using the Neugebauer anisotropic local field model. The distribution function f(β), and hence the higher order parameter ?P ₄?, and nematic pair-potential have been computed at different temperatures in the nematic phase.     

Intramolecular enantiomerism as revealed from Raman optical activity spectrum

An algorithm is employed to retrieve the differential bond polarizabilities (DBP) of the C‐C bonds from the Raman optical activity spectrum of (‐)β‐pinene. (‐)β‐pinene possesses two stereo centers (chiral centers) and a local mirror reflection that interchanges the S type part and R type part in one molecular. It is demonstrated that this local mirror reflection could induce an approximate (or symmetry breaking) mirror reflection that reverses the signs of the DBP of the pair bond coordinates that are related to each other by the mirror reflection.This can be called intramolecular enantiomerism (IE). More cases of IE are discussed by the analysis of (‐)α‐pinene, (R)‐(+)‐4‐isopropyl‐1‐methylcyclohexene and (R)‐(+)‐3‐methylcyclohexanone together with previously studied limonene case. Copyright © 2015 John Wiley & Sons, Ltd.     

Enhancement in age hardenability of sintered Ti–5Fe alloy by Zr addition processed by pulsed electric current sintering

The age-hardenable Ti–5Fe–5Zr (wt. %, 5Zr) alloy has been consolidated by pulsed electric current sintering, following a β solution treatment, and the results are compared with a Ti–5Fe (0Zr) alloy. The precipitation sequence measured at 640°C ageing is β?+?athermal ω?→?β?+?isothermal ω?→?β?+?α. At the peak hardness isothermal ω phase forms at 20?s of ageing. The Zr addition retards the precipitation kinetics of the α phase; as a result, the α phase nucleates at latest at 300?s ageing in the overaged state. Fe is partitioned into β, while it is depleted from the α phases. There is Zr enrichment near the α/β interface when the α phase precipitates due to a solute drag effect; the growth rate of the α phase in the 5Zr alloy is significantly reduced compared with that in the 0Zr alloy.     

L x‐ray fluorescence cross‐sections of heavy elements in the atomic region 57 ≤ Z ≤ 71 excited by 17.78 keV photons

L x‐ray fluorescence cross‐sections (σ_Lα, σ_Lβ, and σ_Lγ) were measured with an accuracy of 6% (except for the Lγ x‐ray line around 8%) for La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Tm, Yb and Lu at an excitation energy of 17.78 keV. Relative intensities I_Kβ/I_Kα and I_Lγ/I_Lα were also measured for the same elements. The measured cross‐sections were compared with experimental and theoretical values. Measurements of the emitted x‐rays were performed using an Si(Li) detector. Copyright © 2004 John Wiley & Sons, Ltd.     

Complexation of aminoglutethimide with native and modified cyclodextrins

Complexations of R(+) and RS(+/?)aminoglutethimide (AGT), the drug used in a treatment of breast and prostate cancer with native and modified cyclodextrins (α‐CD, β‐CD, γ‐CD, 2,6‐di‐O‐methyl‐β‐CD (DM‐β‐CD), 2,3,6‐tri‐O‐methyl‐β‐CD (TM‐β‐CD) and carboxymethyl‐β‐CD (CM‐β‐CD)) were studied. The stability constants were determined with UV–Vis spectrophotometric method at pH 9.0. The NMR data obtained for TM‐β‐CD suggest that the complexation of AGT is possible from both sides of CD molecule. This was confirmed by molecular dynamic simulations. Copyright © 2009 John Wiley & Sons, Ltd.     

Stability of all-trans-β-carotene under ultrasound treatment in a model system: Effects of different factors,kinetics and newly formed compounds

The effects of factors and kinetics of all-trans-β-carotene degradation under ultrasound treatment in a model system were investigated. The compounds of degradation were also tentatively identified by HPLC-DAD, Raman and FT-IR spectroscopy. The type of solvents and temperature were important factors in determining the degradation reaction. Liquid height, ultrasonic intensity and duty cycle of ultrasound exposure only affected the rate of degradation but did not change the nature of degradation. Degradation rate of β-carotene in dichloromethane was the highest. Degradation rate of β-carotene decreased with increasing of temperature. Degradation kinetics of all-trans-β-carotene under ultrasound fitted first-order reaction at ?5 to 15 °C, and fitted second-order reaction at 25 °C. Degradation products included isomers: 15-cis-β-carotene, di-cis-β-carotene and other compounds with function group of C–O.     

Properties of two-photon absorption-induced cavity lasing of an organic dye HEASPI pumped by picosecond infrared laser beam

The first operation of cavity lasing of a two-photon absorption (TPA) organic dye, trans-4-[p-(N-ethyl-N-hydroxyethylamino) styryl]-N-methylpyridinium iodide (HEASPI), by using picosecond infrared laser as pump source is reported in this paper. Temporal profile of cavity lasing shows obvious oscillations, and magnification of the feedback light can be obtained. By using the difference of re-absorption coefficient at different conditions, we explained the blue shift for cavity lasing and superradiance compared with TPA-induced fluorescence. The lifetime of TPA-induced fluorescence is measured to be 134 ps.     

Stereochemistry of a Guaianolide from Cyathocline Purpurea by High Resolution NMR Spectroscopy

The stereochemistry of a sesquiterpene, 6α-hydroxy-4(14),10(15)-guaianadien-8β,12-olide (2) was established by high resolution and 2D-NMR spectroscopy. Careful analysis of the long range couplings along with vicinal spin-spin coupling constants predict a trans fusion of the lactone ring. Further information on the stereochemistry of 2 was obtained from 2D-NOESY and ROESY experiments.     

EPR Study of Single Crystals of PROXYLs

Electron paramagnetic resonance study of the single crystals of two PROXYLs, trans-2,5-bis(4-methylphenyl)-2,5-dimethylpyrrolidine-1-oxy [(±)-1] and trans-2-(4-methylphenyl)-2,5-dimethyl-5-phenylpyrrolidine-1-oxy [(±)-2] was conducted. The obtained spectra were always fitted well by a single Lorentzian. The principal g-values (g _x , g _y , g _z ) of (±)-1 and (±)-2 were determined as (2.00990, 2.00639, 2.00266) and (2.01106, 2.00742, 2.00389), respectively. The profiles of half width at half maximum (HWHM) depending on two polar angles, θ and ϕ, were measured in all directions. The angular profiles of the exchange interaction (|J ₀|) were attempted to be estimated by dividing the experimental HWHM by the calculated total second moment (M ₂ ^tot) with the crystallographic data. For (±)-1, |J ₀| along the c-axis was estimated to be much larger than that along the a- or b-axis. This suggests that (±)-1 is a one-dimensional magnet along the c-axis. Authors' address: Yohei Noda, Electron Spin Chemistry Laboratory, Department of Chemistry, Graduate School of Science, Kyoto University, 606-8502 Kyoto, Japan     

Effects of cooling rate on the microstructure and solute partitioning in near eutectoid Ti–Cu alloys

The effect of cooling rate on eutectoid decomposition in a near eutectoid (Ti-5.5 at.% Cu) alloy has been investigated in a systematic manner by coupling scanning electron microscopy, transmission electron microscopy and atom probe tomography studies. Thus, the competition between nucleation and growth of proeutectoid α plates from pre-existing β grain boundaries, and eutectoid decomposition (α?+?Ti₂Cu) via a pearlitic mechanism has been studied as a function of cooling rate, using a Jominy-end quenched sample that was cooled from the high-temperature single β phase. When the alloy was subjected to very fast cooling (160?K/s), proeutectoid α plates, supersaturated in Cu, are formed along with a highly refined lamellar eutectoid product between these α plates. In contrast, intermediate (9?K/s) and slow (2?K/s) cooling results in considerably coarser proeutectoid α plates as well as lamellar eutectoid products. With the decrease in the cooling rate, there was a substantial increase in the volume fraction of the lamellar eutectoid product and the composition of all decomposition products approached their equilibrium values. Also, the slowest cooled sample (2?K/s) exhibited substantially rougher and irregular interfaces between the proeutectoid α and the lamellar eutectoid product, which seems to promote the cooperative growth of lamellar α?+?Ti₂Cu. Irrespective of the cooling rate, nucleation of the lamellar eutectoid (α?+?Ti₂Cu) product appears to only occur at the interface between the proeutectoid α plates and the β matrix.     

Time-resolved studies on the photoisomerization of a phenylene-silylene-vinylene type compound in its first singlet excited state

In femtosecond laser-flash photolysis experiments, the first singlet excited state of trans-ST, ((E,E)-{1,4-bis(2-dimethylphenylsilyl)ethenyl}benzene) showed a strong S1(π,π^?)-Sn absorption band at 540 nm in acetonitrile and at 550 nm in hexane. The lifetime of this state was determined to be 13.2±2.0 and 11.1±1.5 ps, respectively. Intersystem crossing was shown not to be a principal route for the deactivation of this S1 state of trans-ST. Evidence for this conclusion involved two complementary nanosecond laser-flash photolysis experiments. In one experiment involving direct excitation, no transient absorption spectrum was detected in the 350-650 nm spectral range. Yet, in the second experiment, on triplet sensitization, using xanthone, a transient absorption at 400 nm was tentatively assigned to the triplet state absorption of trans-ST. Photoisomerization was monitored in nanosecond time-resolved bleaching experiments. From these experiments the trans-cis photoisomerization quantum yield was determined to be 0.23 on direct trans-ST excitation. In a xanthone-sensitized stationary-state excitation experiment, the trans-cis isomerization quantum yield was determined to be 0.32. The main deactivation route of trans-ST in its S1 state is repopulation of the ground state directly through internal conversion or with the intermediacy of conformers with twisted geometry.     

Instrumental detection limit and sensitivity of K and L shell X‐ray emission lines of 17Cl, 37Rb,and 38Sr elements using PC‐WDXRF spectrometer

This work was aimed to improve the instrumental detection limit and sensitivity of ₁₇Cl, ₃₇Rb, and ₃₈Sr elements present in solid samples by using the advanced polychromatic wavelength dispersive X‐ray fluorescence spectrometry method. Instrumental measuring parameters, as well as study of calibration curves of K and L shell spectral lines, were evaluated to select the best conditions for ₁₇Cl, ₃₇Rb, and ₃₈Sr quantification. From the results, it was observed that the detection limits of the Rb Kα and Sr Kα spectral lines were lower than those of the Kβ_1,3 and Lα spectral lines. From the calibration curves, it was concluded that Kα spectral lines are more suitable than Kβ_1,3 and Lα lines to identify the traces of ₁₇Cl, ₃₇Rb, and ₃₈Sr elements in different types of solid samples.     

A Comparative Study on Hemp (Cannabis sativa)Essential Oil Extraction Using Traditional and Advanced Techniques

A comparative study of Cannabis sativa(Hemp)essential constituents obtained by using Supercritical Fluid Extraction(SCFE),Steam Distillation(SD)and Hydrodistillation(HD)is presented here.The optimized extraction temperatures were 130,110and 50℃for hydrodistillation,steam distillation and supercritical fluid extraction respectively.The essential oil of C.sativa was analyzed by using Gas chromatography mass spectrometry(GC-MS).A total of 33,30and 31components have been identified in HD,SD and SCFE respectively.Yield of essential oil using SCFE(0.039%)was more than HD(0.025%)and SD(0.035%)extraction respectively.The main component of sesquiterpenes obtained by hydrodistillation at 130℃with their percentages included caryophyllene(40.58%),trans-α-bergamotene(5.41%),humulene(10.97%),cis-β-farnesene(8.53%)and monoterpenes includedα-pinene(2.13%),d-limonene(6.46%),p-cymol(0.65%)and cineole(2.58%)respectively.The main component of sesquiterpenes obtained by SD steam distillation at110℃including caryophyllene(38.60%)trans-α-bergamotene(4.22%),humulene(10.26%),cis-β-farnesene(6.67%)and monoterpenes includedα-pinene(3.21%),d-limonene(7.07%),p-cymol(2.59%)and cineole(3.88%)whereas the more percentages of major components were obtained by SCFE at 50℃included caryophyllene(44.31%),trans-α-bergamotene(6.79%),humulene(11.97%)cis-β-farnesene(9.71%)and monoterpenes includedα-pinene(0.45%),d-limonene(2.13%)p-cymol(0.19%)and cineole(1.38%)respectively.We found yield/efficiency,chemical composition,quality of the essential oils by supercritical fluid extraction superior in terms of modern,green,saving energy and a rapid approach as compared to traditional techniques.     

Comparing long-range corrected functionals in the cis–trans isomerisation of the retinal chromophore

Earlier results for the 11-cis to all-trans isomerisation of the retinal chromophore after photoexcitation, studied using time-dependent density functional theory with the hybrid CAM-B3LYP functional, are compared with new results using other long-range corrected DFT functionals. The TDDFT S₀ and S₁ minimum energy paths have been compared with the approximate coupled-cluster method RI-CC2. All calculations were consistent in producing an additional avoided crossing minimum on the S ₁ minimum energy path lying approximately halfway between the 11-cis and all-trans S₁ minima. In this minimum on the S₁ potential energy surface, the retinal chromophore has inverted bond order in its carbon chain and lower energy than it has in both the 11-cis and all-trans S₁ minima.     

Solid phase synthesis of novel α/β‐tetrapeptides,electrospray ionization mass spectrometric evaluation of their metal cation complexation behavior,and conformational analysis using density functional theory (DFT)

Thirty‐four novel α/β‐tetrapeptides ( 1–34 ) have been prepared employing solid‐phase and in‐parallel synthetic protocols. α/β ‐Tetrapeptides 1 – 34 were prepared by a combination of three α‐amino acid residues (alanine (Ala), phenylalanine (Phe), and isoleucine (Ile)) with one β‐amino acid residue (β³‐homophenylglycine). The corresponding complexes of several selected α/β‐tetrapeptides with alkali, alkaline earth, and transition metals, [tP + M⁺], were evaluated using ion electrospray‐ionization mass spectrometry (ESI‐MS). According to the results from analysis of mixtures, we can conclude that the position of the β‐amino acid is determinant in the affinity toward different metal cations. Computational modeling (DFT, B3LYP 6‐311++G) provided useful information regarding the most likely coordination sites of the metal ions on the receptor α/β‐tetrapeptide 12 , HO₂C‐α‐Phe‐α‐Phe‐α‐Ile‐β³‐hPhg‐NH₂, as well as the conformational changes induced by the metal upon [tP + M⁺] complex formation. Copyright © 2008 John Wiley & Sons, Ltd.     

Raman and infrared spectra of the all-trans, 7-cis, 9-cis, 13-cis and 15-cis isomers of β-carotene: Key bands distinguishing stretched or terminal-bent configurations form central-bent configurations

Raman and infrared spectra in the region of 1800-150 cm⁻¹ were recorded for a set of cis-trans isomers of d̃-carotene, i.e. the all-trans, 7-cis, 9-cis, 13-cis and 15-cis isomers. Spectral comparison revealed Raman and infrared key bands which (1) distinguish stretched or terminal-bent configurations (all-trans, 7-cis and 9-cis) from central-bent configurations (13-cis and 15-cis), and (2) distinguish unmethylated 7-cis and 15-cis configuratios. Keybands (1) include Raman bands at 1160 and 1140 cm⁻¹ and infrared bands at 825 and 775 cm⁻¹ (the intensity varies with the position of the cis-bend) Key bands (2) include Raman bands at 1274 and 962 cm⁻¹ and an infrared band at 741 cm⁻¹ (characteristic of the 7-cis configuration), and also a Raman band at 1247 cm⁻¹ and an infrared band at 775 cm⁻¹ (characteristic of the 15-cis configuration). The normal modes for the key bands were determined by a set of normal coordinate calculations for the isomeric configurations of a simplified model of d̃-carotene. The key bands were mainly related to the C H in-plane bendings, coupled with the CC or C C stretching, or to the C H out-of-plane wagging vibrations, some of which coupled with the CC torsion.