Electron impact and chemical ionization mass spectral analyses of methyl esters species of free mycolic acid fraction from Rhodococcus lentifragmentus

The free mycolic acid fraction from Rhodococcus lentifragmentus was derivatized to methyl esters and further fractionated into saturated (F-0), monounsaturated (F-1) and diunsaturated (F-2) species using argentation-TLC. Methyl esters fractions F-0, F-1 and F-2, accounting for approximately 7.4%, 53.1% and 39.5%, respectively, were analyzed by electron impact (EI) and chemical ionization (CI) mass spectrometries. According to EI-MS, peaks observed for M(+)-18, that were prominent compared to those representing M(+)-32 and M(+)-(18 + 32), indicated that the carbon chain size ranged from C-36 to C-48. The pyrolytic cleavage of methyl mycolates (R(2)-CHOH-CH(R(1))-COOCH3), following the McLafferty rearrangement released fragment ions corresponding to, (a) the alpha-subunit, representing the fatty acid methyl ester (R(1)-CH2-COOCH3), methyl hexadecanoate, methyl tetradecanoate and methyl dodecanoate in decreasing order of relative intensity of peaks, and (b) the beta-subunit, representing the meroaldehyde moiety (R(2)-CHO). The saturated meroaldehyde species exhibited peaks representing meroaldehyde minus 18 mass units in which R(2) ranged from C19H39 to C31H63. The monunsaturated species exhibited peaks representing the meroaldehyde in which R(2) ranged from C19H37 to C31H61; peaks corresponding to meroaldehyde minus 18 mass units appeared only in the most abundant components, C29H57CHO, C27H53CHO, C25H49CHO and C31H61CHO, in a decreasing order of relative abundance. The diunsaturated species exhibited peaks essentially corresponding to meroaldehyde in which R(2) corresponded to C31H59 and C29H55; the latter displayed a relative intensity that was about one-half compared to that of the former. Fractions F-0, F-1 and F-2 showed a more intense pyrolytic fragmentation under CI-MS in contrast to results found under EI-MS. Therefore, peaks representing the alpha-subunit and the beta-subunit were more prominent than the ones representing the fragmentation of the hydrocarbon chain. Moreover, the beta-subunit of saturated species exhibited peaks corresponding to meroaldehyde plus hydrogen, and no dehydration of the beta-subunit occurred in this case. In turn, the beta-subunit of monounsaturated and diunsaturated species showed peaks representing both the meroaldehyde plus hydrogen and its dehydration product plus hydrogen. Thus, the presence of unsaturation in the meroaldehyde subunit of methyl mycolate facilitates appearance of dehydration fragment ions under chemical ionization procedure.

Spectral analysis and control to obtain sub-5 fs pulses by femtosecond filamentation

A spectral-filter method is numerically demonstrated to obtain sub-5 fs pulses by using femtosecond filamentation in fused silica. Instead of employing spectral phase compensation, by properly employing a high-pass filter to select the broadened high-frequency spectra that are located almost in phase in the tailing edge of the self-compressed pulses owing to self-steepening, as short as single-cycle pulses can be obtained. For instance, for an input pulse with a duration of 50 fs and energy 2.2 mu J, the minimum pulse duration can reach to similar to 4 fs (about 1.5 cycles) by applying a proper spectral filter. (C) 2008 Optical Society of America

A novel spectral representation of electromyographic signals

Time/frequency and temporal analyses have been widely used in biomedical signal processing. These methods represent important characteristics of a signal in both time and frequency domain. In this way, essential features of the signal can be viewed and analysed in order to understand or model the physiological system. Historically, Fourier spectral analyses have provided a general method for examining the global energy/frequency distributions. However, an assumption inherent to these methods is the stationarity of the signal. As a result, Fourier methods are not generally an appropriate approach in the investigation of signals with transient components. This work presents the application of a new signal processing technique, empirical mode decomposition and the Hilbert spectrum, in the analysis of electromyographic signals. The results show that this method may provide not only an increase in the spectral resolution but also an insight into the underlying process of the muscle contraction.

Spectral analysis and low-frequency multipath mitigation for kinematic applications

Low-frequency multipath is still one of the major challenges for high precision GPS relative positioning. In kinematic applications, mainly, due to geometry changes, the low-frequency multipath is difficult to be removed or modeled. Spectral analysis has a powerful technique to analyze this kind of non-stationary signals: the wavelet transform. However, some processes and specific ways of processing are necessary to work together in order to detect and efficiently mitigate low-frequency multipath. In this paper, these processes are discussed. Some experiments were carried out in a kinematic mode with a controlled and known vehicle movement. The data were collected in the presence of a reflector surface placed close to the vehicle to cause, mainly, low-frequency multipath. From theanalyses realized, the results in terms of double difference residuals and statistical tests showed that the proposed methodology is very efficient to detect and mitigate low-frequency multipath effects. © 2008 IEEE.

Alkenone analyses of sediment cores from the western Arabian Sea

Records of total organic carbon (TOC) and C37 alkenones were used as indicators for past primary productivity in the western and eastern Arabian Sea. Data from GeoB 3005, an open ocean site in the western Arabian Sea upwelling area, are compared with similar records of GeoB 3007 from the Owen Ridge, Ocean Drilling Program (ODP) Site 723 from the continental margin off Oman and MD 900963 from the eastern Arabian Sea. TOC/C37 alkenone records together with other proxies used to reconstruct upwelling intensity, indicate periods of high productivity in tune with precessional forcing all over the Arabian Sea. Based on their phase-relationship to variations in boreal summer insolation they can be divided into three groups. In the western Arabian Sea the precession-related phasing is different between productivity proxies and those for summer monsoon wind strength and upwelling intensity. TOC and C37 alkenone records from the western Arabian Sea lag the other monsoonal indicators by about 5 kyr, but lead productivity indicators from the eastern Arabian Sea by 3 kyr. Based on the differences in phase relationships associated with the precessional cycling between productivity and monsoonal proxies in the western Arabian Sea it is proposed that the TOC/C37 alkenone signal in the western Arabian Sea document a combined signal of moderate SW monsoon winds and of strengthened and prolonged NE monsoon winds. In the eastern Arabian Sea the phasing hints to coincidence between maximum productivity and stronger NE monsoon winds associated with precession-related maxima in ice volume. In contrast, variations in paleoproductivity at site GeoB 3007 from the Owen Ridge indicate productivity maxima during glacial substages 8.2, 6.2 and 2.2, whereas precessionrelated changes are of only minor importance at this location. The results of frequency analyses confirm that productivity at site GeoB 3007 responds predominantly to glacialinterglacial climate changes, while site GeoB 3005 from the open ocean upwelling region near the Gulf of Aden is dominated by precessional insolation. A possible explanation for the pattern revealed at the Owen Ridge is the periodic NW-SE displacement of the Findlater Jet axis, which separates the region of open ocean upwelling to the northwest from downwelling to the southeast ofthe jet. The carbon isotopes of planktic foraminifera reflect nutrient related d13C variations of dissolved inorganic carbon. The difference between the planktic foraminifera Globigerinoides ruber (w), living in the upper 50 m of the water column, and the deeper Iiving Neogloboquadrina dutertrei (Delta d13Cr-d) of core GeoB 3005 displays nutrient variations in the upwelling area near the Gulf of Aden. The results of cross-spectral analyses between Deltad13Cr-d of GeoB 3005 and proxies for SW monsoon intensity indicate, too, a dissociation of productivity from monsoonal upwelling intensity. Instead, productivity depends mainly on the availability of nutrients, while upwelling intensity of sub-surface water masses seems to be of only secondary importance. Additionally, sea surface temperatures (SSTs) were reconstructed using the unsaturation ratio of C37 alkenones. Alkenone SSTs reflect annual mean temperatures rather than explicitly the season of upwelling. This is evident from alkenone SSTs in a transect of surface sediments extending from the inner Gulf of Aden into the western Arabian Sea. The alkenone-derived SST records of GeoB 3005 from the open ocean upwelling region near the Gulf of Aden and GeoB 3007 from the Owen Ridge reveal similar variations with high SSTs during interglacial and low SSTs during glacial periods. The glacial marine oxygen isotope stage (MIS) 6 remains relatively warm and was not as cold as MIS 3 to 4 and 8 according to the alkenone SST. Similar variation-patterns were reconstructed in the coastal upwelling area off Oman for ODP Site 723 as weIl as in the eastern Arabian Sea for MD 900963, where upwelling is not as pronounced as in the western Arabian Sea. Spectral-analyses indicate that SST changes are in good agreement with the modulation of low-latitude precessional insolation changes by eccentricity. However, they do not show the pronounced cydicity in the precessional frequency band, which is characteristic for variations in paleoproductivity. Although the overall variation pattern is very similar, a dose comparison between the western (GeoB 3005) and the eastern Arabian Sea (MD 900963) shows larger differences between both sites during cold intervals than during periods of warm SSTs. This is attributed to a more effective cooling of surface waters in the western Arabian Sea by prolonged NE monsoon winds during times of expanded Northern Hemisphere ice-sheets, thereby lowering the annual mean SSTs stronger than in the eastern Arabian Sea.

(Table T2) Spectral reflectance record for ODP Site 188-1165

Two main alternating facies were observed at Ocean Drilling Program (ODP) Site 1165, drilled in 3357 m water depth into the Wild Drift (Cooperation Sea, Antarctica): a dark gray, laminated, terrigenous one (interpreted as muddy contourites) and a greenish, homogeneous, biogenic and coarse fraction-bearing one (interpreted as hemipelagic deposits with ice rafted debris [IRD]). These two cyclically alternating facies reflect orbitally driven changes (Milankovitch periodicities) recorded in spectral reflectance, bulk density, and magnetic susceptibility data and opal content changes. Superimposed on these short-term variations, significant uphole changes in average sedimentation rates, total clay content, IRD amount, and mineral composition were interpreted to represent the long-term lower to upper Miocene transition from a temperate climate to a cold-climate glaciation. The analysis of the short-term variations (interpreted to reflect ice sheet expansions controlled by 41-k.y. insolation changes) requires a quite closely spaced sampled record like that provided by the archive multisensor track. Among those, cycles are best described by spectral reflectance data and, in particular, by a parameter calculated as the ratio of the reflectivity in the green color band and the average reflectivity (gray). In this data report a numerical evaluation of spectral reflectance data was performed and substantiated by correlation with core photos to provide an objective description of the color variations within Site 1165 sediments. The resulting color description provides a reference to categorize the available samples in terms of facies and, hence, a framework for further analyses. Moreover, a link between visually described features and numerical series suitable for spectral analyses is provided.

Tree-ring based hydroclimate reconstruction over northern Vietnam from Fokienia hodginsii: eighteenth century mega-drought and tropical Pacific influence

We present here the first statistically calibrated and verified tree-ring reconstruction of climate from continental Southeast Asia.The reconstructed variable is March-May (MAM) Palmer Drought Severity Index (PDSI) based on ring widths from 22 trees (42 radial cores) of rare and long-lived conifer, Fokienia hodginsii (Po Mu as locally called) from northern Vietnam. This is the first published tree ring chronology from Vietnam as well as the first for this species. Spanning 535 years, this is the longest cross-dated tree-ring series yet produced from continental Southeast Asia. Response analysis revealed that the annual growth of Fokienia at this site was mostly governed by soil moisture in the pre-monsoon season. The reconstruction passed the calibration-verification tests commonly used in dendroclimatology, and revealed two prominent periods of drought in the mid-eighteenth and late-nineteenth enturies. The former lasted nearly 30 years and was concurrent with a similar drought over northwestern Thailand inferred from teak rings, suggesting a ``mega-drought'' extending across Indochina in the eighteenth century. Both of our reconstructed droughts are consistent with the periods of warm sea surface temperature (SST)anomalies in the tropical Pacific. Spatial correlation analyses with global SST indicated that ENSO-like anomalies might play a role in modulating droughts over the region, with El Nio (warm) phases resulting in reduced rainfall. However, significant correlation was also seen with SST over the Indian Ocean and the north Pacific,suggesting that ENSO is not the only factor affecting the climate of the area. Spectral analyses revealed significant peaks in the range of 53.9-78.8 years as well as in the ENSO-variability range of 2.0 to 3.2 years.

11-Epi-azadirachtin H from Azadirachta indica

A new tetranortriterpenoid 11-epi-azadirachtin H has been isolated from the methanolic extracts of Azadirachta indica seeds. Its structure is proposed on the basis of various spectral analyses.

Synthesis of new 4-isopropylthiazole hydrazide analogs and some derived clubbed triazole, oxadiazole ring systems - A novel class of potential antibacterial, antifungal and antitubercular agents

In the present study a series of 4-isopropylthiazole-2-carbohydrazide analogs, derived clubbed oxadiazole-thiazole and triazole-thiazole derivatives have been synthesized and characterized by IR, H-1 NMR, C-13 NMR, elemental and mass spectral analyses. The synthesized compounds were evaluated for their preliminary in vitro antibacterial, antifungal and antitubercular activity against Mycobacterium tuberculosis H(37)Rv strain by broth dilution assay method. The synthesized compounds 7a, 7b, 7d and 4 showed an antitubercular efficacy considerably greater than that of the parent 4-isopropyl-1,3-thiazole-2-carbohydrazide 1, suggesting that the substituted 4-isopropylthiazole-2-carbohydrazide moiety plays an important role in enhancing the antitubercular properties of this class of compounds. Compounds 2c, 3, 4, 6d, 7a and 7b exhibited good or moderate antibacterial and antifungal activity. Compounds 4 and 7b showed appreciable cytotoxicity at a concentration of 250 mu M.

Application of z-COSY experiment and its variant for accurate chiral discrimination by H-1 NMR

We report the application of z-COSY experiment and a band selected version of it by employing a selective 90 degrees pulse entitled BASE-z-COSY for precise chiral discrimination, quantification of enantiomeric excess and the analyses of the H-1 NMR spectra of chiral molecules aligned in the chiral liquid crystalline solvent poly-gamma-benzyl-L-glutamate (PBLG). We have demonstrated their applicability for obtaining very high resolution in the H-1 NMR spectra of small organic molecules. It is well known that the commonly employed z-COSY experiment disentangles the spectral complexity, provides pure phase spectra with high resolution, aids in the complete spectral analyses, in addition to yielding information on relative signs of the Couplings. The BASE-z-COSY experiment possesses all these properties, permits the measure of enantiomeric excess, in addition to large saving of instrument time.

Mass Spectrometry Informatics in Systems Biology

Mass spectrometry (MS) became a standard tool for identifying metabolites in biological tissues, and metabolomics is slowly acknowledged as a legitimate research discipline for characterizing biological conditions. The computational analyses of metabolomics, however, lag behind compared with the rapid advances in analytical aspects for two reasons. First is the lack of standardized data repository for mass spectra: each research institution is flooded with gigabytes of mass-spectral data from its own analytical groups and cannot host a world-class repository for mass spectra. The second reason is the lack of informatics experts that are fully experienced with spectral analyses. The two barriers must be overcome to establish a publicly free data server for MS analysis in metabolomics as does GenBank in genomics and UniProt in proteomics. The workshop brought together bioinformaticians working on mass spectral analyses in Finland and Japan with the goal to establish a consortium to freely exchange and publicize mass spectra of metabolites measured on various platforms computational tools to analyze spectra spectral knowledge that are computationally predicted from standardized data. This book contains the abstracts of the presentations given in the workshop. The programme of the workshop consisted of oral presentations from Japan and Finland, invited lectures from Steffen Neumann (Leibniz Institute of Plant Biochemistry), Matej Oresic (VTT), Merja Penttila (VTT) and Nicola Zamboni (ETH Zurich) as well as free form discussion among the participants. The event was funded by Academy of Finland (grants 139203 and 118653), Japan Society for the Promotion of Science (JSPS Japan-Finland Bilateral Semi- nar Program 2010) and Department of Computer Science University of Helsinki. We would like to thank all the people contributing to the technical pro- gramme and the sponsors for making the workshop possible. Helsinki, October 2010 Masanori Arita, Markus Heinonen and Juho Rousu

Metabolism of a monoterpene ketone, R-(+)-pulegone—a hepatotoxin in rat

R-(+)-Pulegone was administered orally to rats and the urinary metabolites were investigated. Six metabolites were isolated and purified using column and thin layer chromatographic techniques. Metabolites were identified by i.r., n.m.r. and mass spectral analyses.The neutral metabolites isolated from urine of rats treated with pulegone (I) were: pulegol (II), 2-hydroxy-2(1'-hydroxy-1'-methylethyl)-5-methylcyclohexanone (III), 3,6-dimethyl-7a-hydroxy-5,6,7,7a-tetrahydro-2(4H)-benzofuranone (V) and menthofuran (VII). Metabolites II and III were also excreted in conjugated form.Acidic metabolites isolated from urine of rats treated with pulegone (I) were: 5-methyl-2(1'-methyl-1'-carboxyethylidene)cyclohexanone (IV) and 5-methyl-5-hydroxy-2(1'hydroxy-'-carboxyethyl)cyclohexanone (VI).

Time-resolved resonance Raman spectroscopic studies on the triplet excited state of fluoranil

Perfluoro substituted organic compounds have attracted attention owing to their unique structure and reactivity induced by the perfluoro effect. Fluoranil, a perfluoro derivative of p-benzoquinone, is the subject of this paper. Although the perfluoro effect in the ground state seems to have been well understood there is no information available about such effects on the excited state. Here, the time-resolved resonance Raman spectra of the triplet excited state of fluoranil are reported along with the Raman excitation profiles (REPs) of the various vibrational modes. The vibrational spectral analyses have been carried out by analogy with the fluoranil ground state, triplet benzoquinone, and triplet chloranil vibrational spectral assignments. Also, the assignments are further supported by the calculated frequencies using ab initio theoretical methods. It is observed that for fluoranil in the triplet excited state, due to the perfluoro effect, the structure is considerably less distorted than benzoquinone and also the electron delocalization in the pi* antibonding orbital is less than that of triplet excited state of benzoquinone.

Metabolic disposition of a monoterpene ketone, piperitenone, in rats: Evidence for the formation of a known toxin, p-cresol

It was shown earlier that the monoterpene ketone, piperitenone (I) is one of the major metabolites of R-(+)-pulegone, a potent hepatotoxin, In the present studies, the metabolic disposition of piperitenone (I) was examined in rats. Piperitenone (I) was administered orally (400 mg/kg of the b. wt./day) to rats for 5 days, The following urinary metabolites were isolated and identified by various spectral analyses: p-cresol (VI), 6,7-dehydromenthofuran (III), p-mentha-1,3,5,8-tetraen-3-ol (IX), p-mentha-1,3, 5-friene-3, 8-diol (X), 5-hydroxypiperitenone (VIII), 7-hydroxypiperitenone (XI), 10-hydroxypiperitenone (XII), and 4-hydroxypiperitenone (VII). Incubation of piperitenone (I) with phenobarbital-induced rat liver microsomes in the presence of NADPH resulted in the formation of five metabolites which have been tentatively identified as metabolites III, VII, VIII, XI, XII, on the basis of gas chromatography retention time and gas chromatography-mass spectrometry analysis. Based on these results, a probable mechanism for the formation of p-cresol from piperitenone (I) via the intermediacy of metabolite III has been proposed.