Relative Abundance Ratios Research Articles

Effect of N2* and N on GaN nanocolumns grown on Si(111) by molecular beam epitaxy

The self-induced growth of GaN nanocolumns (NCs) on SixN1−x/Si (111) is investigated as a function of the ratio of molecular to atomic nitrogen species generated via plasma assisted molecular beam epitaxy. Relative concentrations of the molecular and atomic species are calculated using optical emission spectroscopy. The growth rate (GR), diameter, and density of NCs are found to vary with the molecular to atomic nitrogen species relative abundance ratio within the plasma cavity. With increasing ratio, the GR and diameter of NCs increase while the density of NCs seems to be decreasing. The morphologies and the coalescence of GaN NCs exhibit a trend for molecular/atomic ratios up to 11, beyond which they still change but at a lower rate. The detrimental effect of taperedness of the NCs decreases with increasing molecular/atomic ratios. This is possibly because of reduction in radial growth in NCs due to increase in diffusivity of nitrogen species with increasing ratios.

SYNTHESIS OF THE S-ONLY 122,123,124TE ISOTOPES AND THE SELECTIVE DEPLETION OF 123TE BY ELECTRON CAPTURE PROCESS IN MASSIVE STARS

ABSTRACT We investigate the production ratios of the naturally occurring s-only nuclides 122 − 124 ?> Te by solving a nuclear network in the mass number 120 ≤ A ≤ 124 ?> region under some conditions representing those in the helium–hydrogen inter-shell in low-mass AGB stars as well as those in the helium burning and the carbon burning phases in massive stars. We show that the electron-capture process on 123Te (the natural half-life > 10 16 ?> years) could proceed decisively fast during the late evolutionary phases of massive stars. We thus re-iterate and re-enforce the decades-old notion that detailed analysis of the relative 122 − 124 ?> Te abundances in due consideration of the selective 123Te depletion in massive stars would set a stringent constraint on the s-process modelings. We stress that the relative abundance ratios of 122 − 124 ?> Te in the solar system become quite difficult to decipher if the s-process in massive stars contributes significantly to the synthesis of nuclides in this intermediate A region.

Probing the cool interstellar and circumgalactic gas of three massive lensing galaxies atz= 0.4–0.7

We present multi-sightline absorption spectroscopy of cool gas around three lensing galaxies at z=0.4-0.7. These lenses have half-light radii r_e=2.6-8 kpc and stellar masses of log M*/Ms=10.9-11.4, and therefore resemble nearby passive elliptical galaxies. The lensed QSO sightlines presented here occur at projected distances of d=3-15 kpc (or d~1-2 r_e) from the lensing galaxies, providing for the first time an opportunity to probe both interstellar gas at r~r_e and circumgalactic gas at larger radii r>>re of these distant quiescent galaxies. We observe distinct gas absorption properties among different lenses and among sightlines of individual lenses. Specifically, while the quadruple lens for HE0435-1223 shows no absorption features to very sensitive limits along all four sightlines, strong Mg II, Fe II, Mg I, and Ca II absorption transitions are detected along both sightlines near the double lens for HE0047-1756, and in one of the two sightlines near the double lens for HE1104-1805. The absorbers are resolved into 8-15 individual components with a line-of-sight velocity spread of dv~300-600 km/s. The large ionic column densities, log N>14, observed in two components suggest that these may be Lyman limit or damped Lya absorbers with a significant neutral hydrogen fraction. The majority of the absorbing components exhibit a uniform super solar Fe/Mg ratio with a scatter of <0.1 dex across the full dv range. Given a predominantly old stellar population in these lensing galaxies, we argue that the observed large velocity width and Fe-rich abundance pattern can be explained by SNe Ia enriched gas at radius r~r_e. We show that additional spatial constraints in line-of-sight velocity and relative abundance ratios afforded by a multi-sightline approach provide a powerful tool to resolve the origin of chemically-enriched cool gas in massive halos.

Quantifying and correcting for scat removal in noninvasive carnivore scat surveys

Scat surveys are commonly used to monitor wildlife populations. For carnivores, surveys are typically conducted along roads and trails. Scats available for detection may not reflect scats deposited and variation in disappearance may bias results. Previous research has investigated natural decay and deterioration, but scats deposited along roads or trails are likely influenced to a greater degree by anthropogenic disturbance in some systems. We used experimental plots to evaluate variation in scat removal for two model carnivores, coyote Canis latrans and kit fox Vulpes macrotis, along roads in the Great Basin Desert, USA. Using parametric survival regression, we predicted scat survival and developed persistence‐rate correction factors, which were applied to results from relative abundance scat surveys conducted along 15 transects. Kit fox scats disappeared more rapidly than coyote scats, with 3.3% and 10.6%, respectively, persisting through 42 days. At 14 days, 90.8‐41.7% of scats had been removed across road types. Survival models indicated species, road type, scat position and daily traffic were important predictors of scat persistence. Applying persistence‐rate correction factors to scat survey results altered the inferred relative abundances. Across seasons, mean corrected:uncorrected relative abundance ratios ranged from 1.0–91.2 for coyotes and 1.3–139.3 for kit foxes, with higher mean ratios being influenced by high corrected relative abundances on roads with high traffic volumes. Understanding scat removal rates and patterns can improve inferences from surveys. Persistence‐rate correction factors can be used to reduce bias in indices of abundance, but caution should be used when removal rates are high. Knowledge of spatial variation in persistence can elucidate concerns of false‐positives and false‐negatives in occupancy and capture—recapture studies. Considering the disparity in scat removal between species and among road types and positions, we recommend practitioners quantify and consider variation in removal when interpreting scat survey results.

Intra-individual variability and strontium isotope measurements: A methodological study using 87Sr/86Sr data from Pampa de los Gentiles, Chincha Valley, Peru

Measurement of 87Sr/86Sr relative abundance ratios in tooth enamel is a primary method to determine human paleomobility, and a growing number of studies now use these measurements to also reconstruct individual life histories and geographical origins. Here we test the utility and validity of this method for reconstructing individual life histories. To investigate intra-individual variability, we present results from blinded measurements of strontium isotope ratios in 42 tooth enamel samples from seven individuals found at the late prehistoric site of Pampa de los Gentiles, Chincha Valley, Peru. These samples include enamel that formed early in the development of the individual, as well as enamel that formed during adolescence. This allowed us to investigate normal variation in tooth enamel 87Sr/86Sr ratios. Within the same tooth type in the same individual, differences in 87Sr/86Sr ratios from right and left dental elements ranged from below the limit of detection (<0.00000, canine, Individual 23) to 0.00015 (first premolar, Individual 11). Because of the scale of this difference, these results validate the utility of intra-individual studies that focus on enamel that formed at different times during human development. The data also validate the utility of these strontium isotope ratio measurements when made to the third and fourth decimal place for making archaeological meaningful inferences about paleomobility.

Tentative detection of ethylene glycol toward W51/e2 and G34.3+0.2

How complex organic - and potentially prebiotic - molecules are formed in regions of low- and high-mass star-formation remains a central question in astrochemistry. In particular, with just a few sources studied in detail, it is unclear what role environment plays in complex molecule formation. In this light, a comparison of relative abundances of related species between sources might be useful to explain observed differences. We seek to measure the relative abundance between three important complex organic molecules, ethylene glycol ((CH$_2$OH)$_2$), glycolaldehyde (CH$_2$OHCHO) and methyl formate (HCOOCH$_3$), toward high-mass protostars and thereby provide additional constraints on their formation pathways. We use IRAM 30-m single dish observations of the three species toward two high-mass star-forming regions - W51/e2 and G34.3+0.2 - and report a tentative detection of (CH2OH)2 toward both sources. Assuming that (CH$_2$OH)$_2$, CH$_2$OHCHO and HCOOCH$_3$ spatially coexist, relative abundance ratios, HCOOCH$_3$/(CH$_2$OH)$_2$, of 31 and 35 are derived for G34.3+0.2 and W51/e2, respectively. CH$_2$OHCHO is not detected, but the data provide lower limits to the HCOOCH$_3$/CH$_2$OHCHO abundance ratios of $\ge$193 for G34.3+0.2 and $\ge$550 for W51/e2. A comparison of these results to measurements from various sources in the literature indicates that the source luminosities may be correlated with the HCOOCH$_3$/(CH$_2$OH)$_2$ and HCOOCH$_3$/CH$_2$OHCHO ratios. This apparent correlation may be a consequence of the relative timescales each source spend at different temperatures-ranges in their evolution. Furthermore, we obtain lower limits to the ratio of (CH$_2$OH)$_2$/CH2OHCHO for G34.3+0.2 ($\ge$6) and W51/e2 ($\ge$16). This result confirms that a high (CH$_2$OH)$_2$/CH$_2$OHCHO abundance ratio is not a specific property of comets, as previously speculated.

Characterization of Vanadyl and Nickel Porphyrins Enriched from Heavy Residues by Positive-Ion Electrospray Ionization FT-ICR Mass Spectrometry

Petroporphyrins were enriched and purified from atmospheric residues of two typical heavy oils, Canadian oil sand bitumen (OSAR: Ni, 80 ppm; V, 190 ppm; S, 3.97 wt %) and Chinese Liaohe heavy oil (LHAR: Ni, 68.7 ppm; V, 1.81 ppm; S, 0.36 wt %) by silica-gel chromatography. The separation and purification were confirmed by atomic absorption spectroscopy (AAS) combined with UV–vis spectroscopy, and the petroporphyrins were characterized by positive-ion electrospray ionization (ESI) Fourier transform–ion cyclotron resonance mass spectrometry (FT-ICR MS). Vanadyl and nickel porphyrins in OSAR are simultaneously identified by mass measurement and isotopic fine structure. Vanadyl porphyrins with structures of N4VO, N4VO2, and N4VOS are all detected as protonated analyte ([M + H]+). Both molecular ion (M+•) and protonated analyte ([M + H]+) as well as their corresponding isotopes are observed for N4Ni porphyrins in OSAR and LHAR with an average mass resolving power of over 400000 (m/Δm50%). This is rarely detected by FT-ICR MS using ESI technique previously. Formation of molecular ion can be attributed to the low oxidation potential of nickel porphyrins, the effect of oil matrix on the solution conductivity, and the relatively low flow rate of solution into the capillary. Three more highly unsaturated types of N4VO porphyrins were identified in addition to the six well-documented structures. Compared to N4VO porphyrins, N4VOS porphyrins present higher DBE ranging from 21 to 27 while N4VO2 porphyrins show lower DBE ranging from 18 to 20 and narrower carbon number distribution, suggesting possible different origins of sulfur (pyrolysis of kerogen) and oxygen (diagenesis of chlorophyills). Ni/V and the ratio of relative abundance of ETIO porphyrins to DPEP porphyrins (∑ETIO/∑DPEP) for nickel porphyrins indicate that Liaohe oil and Canadian oil sand bitumen are continental and marine sediments, respectively, and Liaohe oil has a higher maturity. Enrichment by the simple chromatographic method facilitates the mass spectral identification of nickel porphyrins even for heavy residue with low content of nickel and high content of sulfur.

Differentiation of Disaccharide Isomers by Temperature-Dependent In-Source Decay (TDISD) and DART-Q-TOF MS/MS.

Helium direct analysis in real time (He-DART) mass spectrometry (MS) of some compounds, polysaccharides, for example, usually tends to be challenging because of the occurrence of prominent in-source decay (ISD), which was considered as an undesired side reaction, as it complicated the resulting mass spectra. Our approach is to take advantage of an efficient and practical method termed the temperature-dependent ISD (TDISD) technique combined with fragmentation of the dehydrated dimers using DART Q-TOF tandem mass spectrometry for differentiation of disaccharide isomers. In this study, cross-ring cleavages and non-ovalent complexes were detected in the spectra of the saccharides. It was observed that the gas heater temperature had a significant effect on the absence or presence of signal in DART spectra. At high gas temperature, ions in high mass region began to appear. Based on the types of cross-ring cleavages and noncovalent complexes, disaccharide isomers with different linkage positions can be differentiated in both positive and negative ion modes at a lower DART gas temperature. Additionally, anomeric configurations were assigned on the basis of the relative abundance ratio of m/z 198:342 obtained by the comparison of the positive ion mode tandem mass spectrum of an α isomer dimer generated at higher DART gas temperature and that of the corresponding β one. In general, this method is easy, fast, effective, and robust for identifying disaccharide isomers.

A molecular line study towards massive extended green object clumps in the southern sky: chemical properties

We present a molecular line study towards 31 extended green object (EGO) clumps in the southern sky using data from MALT90 (Millimetre Astronomy Legacy Team 90 GHz). According to previous multiwavelength observations, we divide our sample into two groups: massive young stellar objects (MYSOs) and HII regions. Our results seem to support that N2H+ and C2H emissions mainly come from the gas inside quiescent clumps. In addition, we also find that the [N2H+]/[H13CO+] and [C2H]/[H13CO+] relative abundance ratios decrease from MYSOs to HII regions. These results suggest depletion of N2H+ and C2H in the late stages of massive-star formation, probably caused by the formation of HII regions inside. N2H+ and C2H might be used as chemical clocks for massive-star formation by comparing with other molecules such as H13CO+ and HC3N.

Enantioselective photolysis and quantitative chiral analysis of tryptophan complexed with alkali-metalized L-serine in the gas phase.

The enantioselective photolysis of a cold gas-phase noncovalent complex of tryptophan with alkali-metalized L-serine, M(+) (L-Ser)(Trp) (M = Na and Li), was examined using a tandem mass spectrometer containing a variable-temperature ion trap. CO2 loss from Trp in the clusters was enantiomerically selective in ultraviolet excitation with linearly polarized light. M(+) (L-Ser) promoted the enantioselective photolysis of Trp as a chiral auxiliary. The enantioselective photolysis of the D-enantiomer was applied to a quantitative chiral analysis, in which the optical purity of tryptophan could be determined by measuring the relative abundance ratio R of the enantioselective CO2 loss to the chiral-independent evaporation of L-Ser in a single photodissociation mass spectrum of M(+) (L-Ser)(Trp).

The vicissitudes of microorganism and vegetation recorded by lipid biomarkers in the Antarctic penguin habitat and their implications for climate change

Lipid biomarkers of microorganism and vegetation preserved in penguin droppings record historical changes in the West Antarctic climate and environment. n-Alkanes, fatty acids and coprostanols have been determined in sediment core AD6 from penguin droppings in Ardley Island, West Antarctica, using GC or GC/MS/SIM. For n-alkanes, the main carbon number was nC23 with single-peak pattern, ΣC21−/ΣC22+ value was from 0.27 to 0.61, the carbon preference index (CPI) was from 2.97 to 6.12 with significant odd–even predominance (OEP), and these indicate that the vegetation was dominated by mosses and lichens. For fatty acids, the main carbon numbers were nC16:0 and nC24:0 with double-peak pattern, ΣC21−/ΣC22+ value was from 0.35 to 0.77, and the relative abundance ratio of even:odd carbon (CPIA) was from 2.88 to 6.40 with significant OEP. Bacteria invasion index ((iC15:0 + aC15:0)/nC15:0 for fatty acids) showed high contribution of bacteria during 1977–1982, 1948–1953 and 1920–1925, indicating enhanced microbial activities. Meanwhile, CPIA values decreased and extreme microbes contributed fatty acids with low carbon number to penguin dropping strata. Furthermore, the concentration of cholestanol and ratio of cholestanol/cholesterol in penguin dropping strata changed correspondingly, indicating that the microbial degradation played a major role in the increasing ratio of cholestanol/cholesterol during the sedimentation process. The down-core profiles of n-alkanes, fatty acids and coprostanols in penguin dropping strata indicate that extreme microorganism and bacteria play important roles in the relatively simple Antarctic ecological system associated with climate conditions.

A Simple Carbamidomethylation-Based Isotope Labeling Method for Quantitative Shotgun Proteomics

In this study, we present a new isotope-coded carbamidomethylation (iCCM)-based quantitative proteomics, as a complementary strategy for conventional isotope labeling strategies, with providing the simplicity, ease of use, and robustness. In iCCM-based quantification, two proteome samples can be separately isotope-labeled by means of covalently reaction of all cysteinyl residues in proteins with iodoacetamide (IAA) and its isotope (IAA- 13 C2, D2), denoted as CM and iCCM, respectively, leading to a mass shift of all cysteinyl residues to be + 4 Da. To evaluate iCCM-based isotope labeling in proteomic quantifica- tion, 6 protein standards (i.e., bovine serum albumin, serotransferrin, lysozyme, beta-lactoglobulin, beta-galactosidase, and alpha-lactalbumin) isotopically labeled with IAA and its isotope, mixed equally, and followed by proteolytic digestion. The resulting CM-/iCCM-labeled peptide mixtures were analyzed using a nLC-ESI-FT orbitrap-MS/MS. From our experimental results, we found that the efficiency of iCCM-based quantification is more superior to that of mTRAQ, as a conventional noniso- baric labeling method, in which both of a number of identified peptides from 6 protein standards and the less quantitative varia- tions in the relative abundance ratios of heavy-/light-labeled corresponding peptide pairs. Finally, we applied the developed iCCM-based quantitative method to lung cancer serum proteome in order to evaluate the potential in biomarker discovery study

Paraquat exposure and Sod2 knockdown have dissimilar impacts on the Drosophila melanogaster carbonylated protein proteome.

Exposure to Paraquat and RNA interference knockdown of mitochondrial superoxide dismutase (Sod2) are known to result in significant lifespan reduction, locomotor dysfunction, and mitochondrial degeneration in Drosophila melanogaster. Both perturbations increase the flux of the progenitor ROS, superoxide, but the molecular underpinnings of the resulting phenotypes are poorly understood. Improved understanding of such processes could lead to advances in the treatment of numerous age-related disorders. Superoxide toxicity can act through protein carbonylation. Analysis of carbonylated proteins is attractive since carbonyl groups are not present in the 20 canonical amino acids and are amenable to labeling and enrichment strategies. Here, carbonylated proteins were labeled with biotin hydrazide and enriched on streptavidin beads. On-bead digestion was used to release carbonylated protein peptides, with relative abundance ratios versus controls obtained using the iTRAQ MS-based proteomics approach. Western blotting and biotin quantitation assay approaches were also investigated. By both Western blotting and proteomics, Paraquat exposure, but not Sod2 knockdown, resulted in increased carbonylated protein relative abundance. For Paraquat exposure versus control, the median carbonylated protein relative abundance ratio (1.53) determined using MS-based proteomics was in good agreement with that obtained using a commercial biotin quantitation kit (1.36).

The impact of thermal maturity level on the composition of crude oils, assessed using ultra-high resolution mass spectrometry

We have examined, using a 12Tesla FTICR-MS instrument, the impact of varying thermal maturity level on a suite of 9 related crude oils charged from source rocks covering most of the liquid petroleum generating portion of the oil window (0.68–1.11% vitrinite reflectance equivalent (%Re)). The sample suite was analyzed as whole oils under three different conditions, electrospray ionization (ESI) in positive and negative ion mode to analyze basic and acidic components, respectively, and atmospheric pressure photoionization (APPI) in positive ion mode, for sulfur and hydrocarbon species.Increasing oil maturity level had a strong influence on the composition of all compound classes in the oils with several major observations evident:The relative apparent abundances of all heteroatom containing compound classes detected in this study, using all ionization modes, decrease systematically with increasing oil maturation levels. Both aromatic hydrocarbons, detectable in APPI mode, and NSO compound classes (detectable in both ESI and APPI modes), as broad classes, are becoming more aromatic (shift to a greater predominance of higher DBE group members) and dealkylated (decreasing average molecular mass of individual compound groups), with increasing maturation level in the oil suite. Several putative oil maturity level dependent, molecular ratios were identified in the study. Of particular note, the relative abundance ratios of heteroatom compound classes tentatively identified as alkylated carbazoles, quinolines and benzothiophenes, compared to their benzannulated homologues are very sensitive to maturation level. Several groups of compounds show interesting and specific carbon number distributions, suggesting there may be hints of specific molecular markers in the FTICR-MS data. One observation of note is the strong increase in the relative abundance of protonated hydrocarbon components with DBE 5. We speculate this might reflect the presence of previously unreported higher molecular weight diamondoid (diamantane) species in oils with up to 40 carbon atoms or more, at advanced maturity levels. Such species may prove very valuable as molecular markers in highly mature fluids, such as those currently being produced from some shale reservoirs. Covariation of quantitative GC–MS data for alkylated hetero aromatic sulfur and nitrogen compounds in this oil suite, together with the corresponding FTICR-MS data from compounds believed to be, based on accurate mass, alkylated sulfur and alkylated nitrogen compounds, suggests that FTICR-MS already has some very rudimentary quantitation capabilities.

Identification and characterization by LC-UV-MS/MS of melanotan II skin-tanning products sold illegally on the Internet.

New methods were developed and validated to determine the identity, contents, and purity of samples of melanotan II, a synthetic melanocortin receptor agonist, sold in vials as injectable skin-tanning products that were purchased from three online shops. Methods were based on liquid chromatography with ultra-violet detection (LC-UV) at wavelength 218 nm, and tandem mass spectrometric detection (MS/MS) after collision-induced fragmentation of the double charged [M+2H](2+) precursor ion (m/z 513). Identification of melanotan II was verified by correct chromatographic retention time, and relative abundance ratios of five qualifying fragment ions. LC-UV was used to quantify melanotan II as well as impurities. Method validation was performed with reference to guidelines for assessing active substances in authorized medicinal products to reach acceptable accuracy and precision. Vials from two shops contained unknown impurities ranging from 4.1 to 5.9%; impurities from one shop were below the quantification limit. The total amount of melanotan II in vials ranged between 4.32 and 8.84 mg, although each shop claimed that vials contained 10 mg melanotan II. A broad range of drugs used for enhancement purposes can be obtained from the illicit market. However, users of these drugs may be exposed to a range of potential harms, as shown in this study, given that these products are manufactured, distributed and supplied from an illicit market.

Possible Prognostic Value of BORIS Transcript Variants Ratio in Laryngeal Squamous Cell Carcinomas – a Pilot Study

BORIS is a paralog of a highly conserved, multi-functional chromatin factor CTCF. Unlike CTCF, which has been shown to possess tumor-suppressive properties, BORIS belongs to the "cancer/testis antigen" family normally expressed only in germ cells and aberrantly activated in a variety of tumors. The consequences of BORIS expression, relative abundance of its isoforms, and its role in carcinogenesis have not been completely elucidated. It activates transcription of hTERT and MYC, genes relevant for laryngeal carcinoma progression. In this study, BORIS expression has been analyzed at the transcriptional level by RT-PCR and protein level by semi-quantitative immunohistochemistry in 32 laryngeal squamous cell carcinomas and adjacent non-tumorous tissue. BORIS was detected in 44 % (14/32) laryngeal squamous cell carcinoma samples, while it was detected only in one normal, tumor-adjacent tissue sample. Tree based survival analysis, using the recursive partitioning algorithm mvpart, extracted the ratio of relative abundance of BORIS transcript variants containing exon 7 (BORIS 7+) and those lacking exon 7 (BORIS 7-) as an independent prognostic factor associated with disease relapse during a 5-year follow-up period. Patients having BORIS 7+/BORIS 7- ratio ≥1 had a higher rate of disease relapse than patients with BORIS 7+/BORIS 7- ratio <1. Hazard ratio for that group, based on Cox Proportional Hazard Regression, was 3.53. This is the first study analyzing expression of BORIS protein and transcript variants in laryngeal squamous cell carcinoma relative to its possible prognostic value for recurrence and overall survival.

Comparison of the Membrane Proteome of Virulent Mycobacterium tuberculosis and the Attenuated Mycobacterium bovis BCG Vaccine Strain by Label-Free Quantitative Proteomics

The Mycobacterium tuberculosis membrane is rich in antigens that are potential targets for diagnostics and the development of new vaccines. To better understand the mechanisms underlying MTB virulence and identify new targets for therapeutic intervention, we investigated the differential composition of membrane proteomes between virulent M. tuberculosis H37Rv (MTB) and the Mycobacterium bovis BCG vaccine strain. To compare the membrane proteomes, we used LC-MS/MS analysis in combination with label-free quantitative proteomics, utilizing the area under the curve of the extracted ion chromatograms of peptides obtained from m/z and retention time alignment of MS1 features. With this approach, we obtained relative abundance ratios for 2203 identified membrane-associated proteins in high confidence. Of these proteins, 294 showed statistically significant differences of at least two fold in relative abundance between MTB and BCG membrane fractions. Our comparative analysis detected several proteins associated with known genomic regions of difference between MTB and BCG as being absent, which validated the accuracy of our approach. In further support of our label-free quantitative data, we verified select protein differences by immunoblotting. To our knowledge, we have generated the first comprehensive and high-coverage profile of comparative membrane proteome changes between virulent MTB and its attenuated relative BCG, which helps elucidate the proteomic basis of the intrinsic virulence of the MTB pathogen.

Effect of Aggregation Pheromone Trap of &lt;I&gt;Riptortus pedestris&lt;/I&gt; (Hemiptera: Alydidae) on the Distribution and Composition of Its Egg Parasitoids

The aggregation pheromone of Riptortus pedestris (F.) (Hemiptera: Alydidae) is known to attract its egg parasitoids Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) and Gryon japonicum (Ashmead) (Hymenoptera: Scelionidae). Distribution and composition of these egg parasitoids were compared in a soybean field in the presence and absence of aggregation pheromone-baited traps for two consecutive years. Three traps were installed on the edge of a soybean field, first without and then with aggregation pheromone in a before-after design, and changes in parasitism were assessed on nonviable host eggs released at distances of 9, 18, 27, and 36 m from the trap. A significant interactive effect of pheromone installation and distance was found in egg parasitism by both parasitoids. Parasitism on eggs recovered from 9 m away was up to 2.2 and 3.2 times higher in presence of pheromone than without pheromone for O. nezarae and G. japonicum, respectively. Parasitism by O. nezarae was always higher than that by G. japonicum, but their relative abundance, clutch size, and sex ratio were not affected by pheromone installation, irrespective of distance from the trap. In conclusion, aggregation pheromone increases abundance of parasitoids up to 18 m from trap installation points and does not affect the relative abundance of parasitoid species.

Simultaneous determination of 6 forbidden colorants in cosmetics by high performance liquid chromatography-tandem mass spectrometry

A method of high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) has been established for the simultaneous determination of six forbidden colorants including Sudan IV, Acid Violet 49, Sudan Blue 2, Solvent Red 49, Basic Violet 1 and Pigment Orange 5 in cream and powdery matrix cosmetics. The samples were extracted with ethanol-acetonitrile (3:2, v/v) solution by ultrasonic technique for 20 min, then centrifuged for purification and enriched by nitrogen blowing sequentially. The analytes were isolated on a Luna C18 column (150 mm x 2.1 mm, 5 microm) by gradient elution with methanol and 10 mmol/L ammonium acetate as the mobile phases, and detected by MS/MS in the multiple reaction monitoring (MRM) mode. The qualitative analysis was based on the retention time and the relative abundance ratio of the characteristic ions, and the quantitative analysis on calibration curve method. The results showed that the limits of quantification (LOQ, S/N= 10) of the six colorants ranged from 0.1 to 10 microg/kg and the average recoveries were from 86.67% to 98.22% with the relative standard deviations (RSDs) from 4.01% to 7.01%. The method is simple and rapid with high sensitivity and good reproducibility, and suitable for the determination of the six forbidden colorants in cosmetics.

Element abundances at high redshift: MIKE observations of sub-damped Lyman α absorbers at 1.7 &lt; z &lt; 2.4

We present chemical abundance measurements from high-resolution observations of five sub-damped Lyman α absorbers (sub-DLAs) at 1.7 < z < 2.4 observed with the Magellan Inamori Kyocera Echelle (MIKE) spectrograph on the 6.5-m Magellan II (Clay) telescope. Lines of Zn ii, Mg i, Mg ii, Al ii, Al iii, S ii, Si ii, Si iv, C ii, C ii*, C iv, Ni ii, Mn ii and Fe ii were detected and column densities were determined. The metallicity of the absorbing gas, inferred from the nearly undepleted element Zn, is in the range of <−0.95 to +0.25 dex for the five absorbers in our sample, with three of the systems being near-solar or supersolar. We also investigate the effect of ionization on the observed abundances using photoionization modelling. Combining our data with other sub-DLA and DLA data from the literature, we report the most complete existing determination of the metallicity versus redshift relation for sub-DLAs and DLAs. We confirm the suggestion from previous investigations that sub-DLAs are, on average, more metal rich than DLAs and may evolve faster. We also discuss relative abundances and abundance ratios in these absorbers. The more metal-rich systems show significant dust depletion levels, as suggested by the ratios [Zn/Cr] and [Zn/Fe]. For the majority of the systems in our sample, the [Mn/Fe] versus [Zn/H] trend is consistent with that seen previously for lower redshift sub-DLAs. We also measure the velocity width values for the sub-DLAs in our sample from unsaturated absorption lines of Fe ii λλ2344, 2374, 2600 Å, and examine where these systems lie in a plot of metallicity versus velocity dispersion. Finally, we examine cooling rate versus H i column density in these sub-DLAs, and compare this with the data from DLAs and the Milky Way interstellar medium. We find that most of the systems in our sample show higher cooling rate values compared to those seen in the DLAs.