Retention Indices Research Articles

Exotic Spartina alterniflora invasion enhances sediment N-loss while reducing N retention in mangrove wetland

Wide and rapid Spartina alterniflora invasion has threatened the sustainability of coastal wetlands of China, and has a significant impact on sediment biogeochemical cycle. However, the effects of exotic Spartina alterniflora invasion on sediment dissimilatory nitrates (NOx−) reduction processes and mechanisms underlying these pathways in mangrove wetlands have not been well studied. Here, denitrification (DEN), anaerobic ammonium oxidation (ANA) and dissimilatory nitrate reduction to ammonium (DNRA) rates, contributions (DEN%, ANA%, and DNRA%), associated functional genes (nirS, anammox 16S rRNA and nrfA) and controlling factors were investigated in surface sediments (0–5 cm) in mangrove and Spartina alterniflora communities and ecotone of the Zhangjiang Estuary, China. Significant spatial differences in DEN, DNRA, DEN%, and DNRA% were found among different plant communities (p < 0.05 for all). DEN is the dominant pathway of NOx− reduction processes in Spartina alterniflora community (87–89 %) and ecotone (75–78 %), while DEN (41–51 %) and DNRA (36–51 %) compete with each other in mangrove community. Organic matter was the most dominating factor controlling DEN and DNRA rates. Without accounting for confounding factors, Spartina alterniflora invasion significantly reduced the nitrogen retention index (NIRI), causing a large amount of nitrogen (N) loss in wetlands. We estimated that Spartina alterniflora invasion has increased sediment N-loss (831.09 ± 55.16 t N yr−1) but reduced N retention (783.48 ± 37.73 t N yr−1) in mangrove habitats of China within last 40 years (1980–2020). Thus, Spartina alterniflora invasion enhances sediment N-loss while reducing N retention in mangrove wetlands, which may threaten the mangrove buffer function and wetland N pools protection in estuarine and coastal ecosystems.

Total-evidence phylogeny and evolutionary morphology of New World pitvipers (Serpentes: Viperidae: Crotalinae).

Crotalines (pitvipers) in the Americas are distributed from southern Canada to southern Argentina, and are represented by 13 genera and 163 species that constitute a monophyletic group. Their phylogenetic relationships have been assessed mostly based on DNA sequences, while morphological data have scarcely been used for phylogenetic inquiry. We present a total-evidence phylogeny of New World pitvipers, the most taxon/character comprehensive phylogeny to date. Our analysis includes all genera, morphological data from external morphology, cranial osteology and hemipenial morphology, and DNA sequences from mitochondrial and nuclear genes. We performed analyses with parsimony as an optimality criterion, using different schemes for character weighting. We evaluated the contribution of the different sources of characters to the phylogeny through analyses of reduced datasets and calculation of weighted homoplasy and retention indexes. We performed a morphological character analysis to identify synapomorphies for the main clades. In terms of biogeography, our results support a single colonization event of the Americas by pitvipers, and a cladogenetic event into a Neotropical clade and a North American/Neotropical clade. The results also shed light on the previously unstable position of some taxa, although they could not sufficiently resolve the position of Bothrops lojanus, which may lead to the paraphyly of either Bothrops or Bothrocophias. The morphological character analyses demonstrated that an important phylogenetic signal is contained in characters related to head scalation, the jaws and the dorsum of the skull, and allowed us to detect morphological convergences in external morphology associated with arboreality.

Diversity of volatile organic compounds in 14 rose cultivars

ABSTRACT This study illustrates the importance of multivariate analysis in profiling the levels of 104 volatiles across 14 modern rose cultivars obtained using headspace gas chromatography–mass spectrometry analysis. Despite differences in the abundance of volatiles, the cultivars ‘Lady Emma Hamilton’, ‘Golden Celebration’ and ‘The Poet’s Wife’ share similar profiles of volatile organic compounds (VOCs) and the absence of phenethyl alcohol, which is usually associated with a characteristic ‘rose’ fragrance. R. ‘Hansa’ is the cultivar with the greatest abundance of volatiles, with high levels of acyclic monoterpenes and aromatic compounds. No monoterpenes were detected from the climbing rose R. ‘August Gervais’. The study revealed that highly fragrant cultivars tend to produce VOCs in higher intensity and greater diversity. These findings also demonstrate the potential of using headspace analysis to compare the natural aromas of rose cultivars, which provides information to inspire innovation in the perfumery and food industries. Abbreviations AMT, acyclic monoterpenes; ARM, aromatic compounds; CMT, cyclic monoterpenes; GLV, green leaf volatiles; HEX, C6 lipid derivatives; OTH, other volatiles; PCoA, principal coordinates analysis; PEA, phenethyl alcohol; RI, retention index; SSQ, sesquiterpenes; TD-GC-MS, thermal desorption-gas chromatography-mass spectrometry; VOC, volatile organic compounds.

Analysis of Empetrum nigrum L. lipophilic secondary metabolites, their metabolomic profiles and antioxidant activity

ABSTRACT Fourteen hexane-soluble polyphenolic secondary metabolites were previously isolated as individual compounds from Empetrum nigrum L. and identified as three bibenzyls, four 9,10-dihydrophenanthrenes, two chalcones, four dihydrochalcones and one flavanone. In this study, the mass-spectra and retention indexes (RI) of compounds 1-14 without prior derivatization were obtained and the resulting fragmentation pathways rationalized in accordance with literary data and the compounds structures. Preliminary differences in metabolite composition were assessed by comparative profiling using GC-MS chromatography combined with multivariate data analysis for a limited amount of E. nigrum n-hexane extracts obtained from plants growing in three different geographic locations. To characterize antioxidant capacity of isolated compounds 1-14 we used our well-established model based on reactive oxygen species (ROS) production by activated human platelets and showed that most of the examined polyphenols act as antioxidants by inhibition of ROS production.

Construction of Chemical Libraries of Volatile Compounds by Combinatorial Synthesis of Homologous Mixtures: Alk-4-en-1-ols, Alk-4-enals and Methyl Alk-4-enoates.

A compound library of sixty six linear compounds, eleven representatives of six molecular families: (E)- and (Z)-isomers of alk-4-en-1-ols, alk-4-enals, and methyl alk-4-enoates, was prepared by combinatorial syntheses to allow the creation of a mass spectral database directly usable for their identification in GC/MS analyses. We demonstrate here that compound libraries can be prepared by combinatorial syntheses using long linear synthetic sequences, i. e., eight step in the case of 4-enals. The resulting mixtures of homologues are still perfectly exploitable to deliver the requested information such as clean mass spectra and good gas chromatographic retention indices.

Comparison of 18F-FDG PET/CT imaging with different dual time 18F-FDG PET/CT with forced diuresis in clinical diagnosis of prostate cancer.

The aim of this study was to compare the capability of different dual time (interval 1, 2, 3, or 4 hours) 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) with forced diuresis to diagnose prostate cancer (PCa). A retrospective review of 273 male patients from March 2009 to June 2019, with any focal 18F-FDG uptake in the prostate gland during PET/CT imaging. Early PET/CT imaging was performed 60 minutes after FDG injection. Delayed imaging was performed 1 to 4 hours after diuretic injection. For prostate lesions with increased 18F-FDG uptake, a spheroid-shaped volume of interest was drawn, including the entire lesion, and the maximum standard uptake value (SUVmax) of the lesion was measured. The SUVmax > 2.5 after delayed imaging and the retention index > 15% were used as the diagnostic criteria for PET/CT in the diagnosis of PCa. Otherwise, it was diagnosed as the benign prostate disease. The final diagnosis was based on histological examination, associated imaging studies, or/and clinical follow-up. The results of inter-group comparison showed that the SUVmax of 1-, 2-, 3-, and 4-hour delayed imaging after diuresis in PCa group was significantly higher than that in control group (P < .05), but there was no statistical difference in SUVmax of early imaging between PCa and control group (P > .05). And the retention index of PCa group that delayed 1, 2, 3, and 4 hours after diuresis were significantly higher than those of control group, respectively (P < .05). The diagnostic sensitivity of imaging delayed 1, 2, 3, and 4 hours after diuresis was 68.8%, 81.2%, 85.7 %, and 71.4%, the specificity was 52.5%, 74.5%, 70.6%, and 65.0%, and the accuracy was respectively 58.2%, 77.4%, 76.4%, and 67.6%, the positive predictive values were 44.0%, 68.9%, 64.3%, and 58.8%, and the negative predictive value were 75.6%, 85.4%, 88.9%, and 76.5%, respectively. 18F-FDG PET/CT imaging as an imaging tool lacks certain specificity in the diagnosis of PCa, regardless of whether the imaging is delayed. The main advantage of delayed diuretic imaging in PCa is that it can significantly improve the sensitivity, especially the diagnostic effect delayed 2 hours after diuresis is better.

Chemical Composition, Antibacterial Test, and Antioxidant Activity of Essential Oils from Fresh and Dried Stropharia rugosoannulata

The essential oils, respectively, from fresh and dried Stropharia rugosoannulata fruiting bodies, an important edible mushroom, have been studied for their chemical composition, antibacterial capacity, and antioxidant activity. The essential oils were obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS) combined with Kovats retention index. The oils’ antibacterial test was evaluated by the microdilution method against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa, and antioxidant activity was determined through DPPH radical scavenging activity and ferric reducing power. Twenty-nine components were identified from the fresh mushroom, and the compositions were mainly dominated by hydrocarbons (54.72%), acids (32.99%), esters (5.07%), and terpenic compounds (0.96%). Thirty-five components were identified from the dried sample, and acids (31.22%), terpenic compounds (28.7%), alcohols (12.7%), and ketones (10.48%) were the major compounds. Strong antibacterial capacity and obvious antioxidant activity were observed for both essential oils from the fresh and dried mushrooms.

Caryophyllene-Rich Essential Oils of Two Species from Southern Côte d’Ivoire: Guibourtia ehie (A. Chev.) J Léonard (Caesalpiniaceae) and Oricia suaveolens (Engl.) Verd. (Rutaceae)

The essential oils of Oricia suaveolens and Guibourtia ehie from Southern Côte d’Ivoire were extracted by hydrodistillation then analyzed by gas chromatography in combination with retention indices [GC(RI)], gas chromatography coupled with mass spectrometry (GC-MS) and nuclear magnetic resonance of carbone-13 (13C NMR) And described here for the first time. A total of 42 compounds were identified in the essential oils of the leaves of G. ehie while 55, 40 and 23 components were identified in the leaves, stem bark and root bark oils of O. suaveolens, respectively. Essential oils samples were dominated by sesquiterpenes and (E)-β-caryophyllene was the major compound common to all samples: G. ehie leaf oil contained (E)-β-caryophyllene (26.9–40.8%), α-humulene (syn. α-caryophyllene) (6.7–9.7%), β-elemene (5.5–9.5%) and germacrene D (5.6–8.1%); O. suaveolens, leaf oil contained (E)-β-caryophyllene (33.5–39.3%), (E)-β-farnesene (5.9–9,3%), caryophyllene oxide (2.1–7.7%) and α-humulene (4.0–4.6%); stem bark oil contained α-humulene (38.3–45.8%) and (E)-β-caryophyllene (34.7–41.6%); root bark oil contained α-humulene (36.1–47.9%) and (E)-β-caryophyllene (34.3–43.3%). This study highlighted the abundant presence of (E)-β-caryophyllene, a phytocannabinoïd sesquiterpene with countless biological properties, in two plant species: Guibourtia ehie and Oricia suaveolens.

Benzonaphthothiophene: Molecular Indicators for Thermal Maturity

Benzonaphthothiophenes (BNTs) were firmly identified in coals by comparison with retention indices reported in the literature. The thermodynamic stabilities of BNTs were calculated by quantum chemical computations, and their stability sequence is as follows: [2,1]BNT > [2,3]BNT > [1,2]BNT. The BNT isomers are ubiquitous in coal samples from the Xihu Depression and the Ordos Basin. This study reveals the effects of thermal maturity on the distributions of BNTs in coals, where the relative abundances of [1,2]BNT and [2,3]BNT to [2,1]BNT were observed to be mainly controlled by thermal maturation conditions. Combining with theoretical calculations of thermodynamic stability, two benzonaphthothiophene maturity indicators, defined as BNTR-1 ([2,1]BNT/[2,3]BNT) and BNTR-2 ([2,1]BNT/([1,2]BNT + [2,3]BNT)), were proposed. Two preliminary calibrations of BNTR-1 and BNTR-2 against measured vitrinite reflectance (%Ro) were established, and the relationships are as follows: %Rc = 5.5 × BNTR-1/100 + 0.5 (%Ro >0.9) and %Rc = 15 × BNTR-2/100 + 0.5 (%Ro > 0.9), respectively. BNTR-1 and BNTR-2 have good correlations with the widely used molecular maturity parameters. The good correlations with vitrinite reflectance and maturity parameters suggest that BNTR-1 and BNTR-2 are useful indicators in evaluating the maturity for sedimentary organic matter at high levels of thermal stress. The accuracy of the BNT ratio ([2,1]BNT/[1,2]BNT) must be kept in mind when it is used as a migration tracer of oil generated at a high thermal maturation stage. There is no clear trend for the absolute concentrations of BNTs with increasing pristane/phytane and gammacerane/C30 hopane values, suggesting that the redox conditions and water salinity during deposition may have little influence on the generation of BNTs. This study can expand the understanding of the distribution and geochemical significance of complex sulfur-containing organic compounds in sedimentary organic matter.

Evidence for the Hydration of Some Organic Compounds during Reverse-Phase HPLC Analysis.

Some polar analytes (X) can reversibly form hydrates in water-containing eluents under the conditions of reversed-phase HPLC analysis, X + H2O ⇄ X × H2O. One of the methods to detect their formation is the recurrent approximation of the net retention times of such analytes, tR(C + ΔC) = atR(C) + b, where ΔC = const is the constant step in the variation of the organic modifier content of an eluent. These dependencies are linear if hydrates are not formed, but in the case of hydrate formation, they deviate from linearity under high water content. It has been shown that UV spectroscopic parameters, namely, relative optical densities: Arel = A(λ1)/A(λ2), depend on eluent composition for some organic compounds, but their variations cannot be used as indicators for hydrate formation. The coefficients that characterize the dependence of the analyte retention indices on the organic component concentration of an eluent, dRI/dC, appeared to be the most informative additional criterion for hydration. The values of these coefficients for most polar analytes are largely negative (dRI/dC < 0), whereas, for nonpolar compounds, they are largely positive (dRI/dC > 0).

Prediction of Clinical Molecular Typing of Breast Invasive Ductal Carcinoma Using 18F-FDG PET/CT Dual-Phase Imaging

To investigate the diagnostic value of Fluorine-18-labeled 2-fluoro-2-deoxy-D-glucose positron emission tomography and computed tomography (18F-FDG PET/CT) dual-phase imaging for the different molecular subtypes of invasive ductal carcinoma of the breast. Clinical imaging data of 164 women with invasive ductal carcinoma of the breast confirmed by pathology who underwent 18F-FDG PET/CT dual-phase imaging were retrospectively analyzed. The maximum standard uptake values (SUVmax) of the early and delayed phases of the lesion were measured and recorded as SUVmax1 and SUVmax2, respectively, and the retention index (RI) was calculated. We analyzed the change rule of SUVmax1, SUVmax2, and RI for the different molecular subtypes and molecular marker expression groups. The diagnostic threshold of different molecular marker expression status was determined using receiver operating characteristic curve analysis. SUVmax1 and SUVmax2 were highest in the TNBC group and lowest in the luminal A group (p<0.001). TNBC and HER2 overexpression groups had higher RI than the luminal A and B groups (p<0.001), with no significant difference between the TNBC and HER2 overexpression groups or between the luminal A and B groups (p=0.640 and 0.345, respectively). The ER- and PR-negative groups had significantly higher SUVmax1, SUVmax2, and RI than the PR-positive group (p<0.001). The HER2-positive group had higher SUVmax1 and SUVmax2 than the negative group (p<0.001). The Ki67 overexpression group had higher SUVmax1 and SUVmax2 levels than the low expression group (p<0.001). There was no significant difference in RI between HER2-positive and negative groups or between Ki67 high and low expression groups (p=0.904 and 0.216, respectively). For ER-negative and positive expression status, the maximum area under the curve (AUC) of SUVmax2 was 0.852, diagnostic threshold was 10.87, sensitivity was 79.6%, and specificity was 74.5%. For PR-negative and positive expression status, the AUC of SUVmax2 was 0.858, diagnostic threshold was 10.45, sensitivity was 83.1%, and specificity was 75.3%. For HER2-negative and positive expression status, the AUC of SUVmax1 was 0.714, diagnostic threshold was 9.28, sensitivity was 79.6%, and specificity was 60.9%. For Ki67 high- and low expression status, the AUC of SUVmax2 was 0.915 at maximum, diagnostic threshold was 10.21, sensitivity was 83.4%, and specificity was 93.9%. 18F-FDG PET/CT dual-phase imaging facilitates the prediction of the expression of molecular markers and subtypes of invasive ductal carcinoma of the breast and the development of more tailored treatment plans for patients with this disease.

Synergistic effects of the use of metakaolin, sand and water on the properties of cementitious composites for 3D printing

3D concrete printing (3DCP) is a construction technique based on the deposition of successive layers of a cementitious composite without the need for conventional formwork. For the technique to be applied it is necessary that the cementitious composite used allows the passage in continuous flow in a 3D printing nozzle (extrusion capacity) and presents low deformation of the printed layers (buildability). In this perspective, the aim of this study was to understand the influence of Metakaolin (MK), sand and water incorporation on the extrusion capabilities and buildability of cementitious composites for 3D printing. The analysis was designed in a simplex lattice mixture statistical experimental planning. Extrusion ability was evaluated using an experimental flow rate by extruder mill and slump flow. Buildability was analyzed by the maximum number of printed layers, shape retention index, layer thickness variation, and squareness deviation in printed blocks. The squeeze flow test was carried out as a parameter for both printing properties. The water/binder ratio was the most determinant variable in extrusion capacity for its responsibility to fluidize the mixture. Increasing the sand content improves buildability but reduces the application time. On the other hand, MK presented the advantage of controlling viscosity and maintaining good fluidity over time, due to a slower setting. There was a significant interaction between sand and MK in the packing of grains, increasing the properties related to extrusion. It was possible to print with a 30% MK content by adjusting the water. The yield stress was directly related to the flow rate, validating the experimental methodology created. Thus, it was possible to understand the effect of each component, as well as their interactions.

Comparison of Gas-Chromatographic Retention Parameters of Aliphatic Enyne Alcohols with the Data for Their Structural Analogues

We studied the regularities of gas-chromatographic retention indices of aliphatic enyne alcohols containing С=С and С≡С bonds in the molecule (14 secondary and two tertiary homologues) on standard nonpolar polydimethylsiloxane stationary phases, which have not been characterized in sufficient detail earlier. Using homologous increments of retention indices iRI = RI – 100x, where х = int(M/14), М is the molecular weight number, and 14 is the mass number of the CH2 homological difference, one can compare data for structural analogs, including alkanols, alkenols, and alkynols. The features of comparing iRI values for compounds belonging to different homologous groups y ≡ M(mod14), for example, CnH2n+2O (y = 4), CnH2nO (y = 2), CnH2n–2O (y = 0), and CnH2n–4O (y = 12), are discussed. The main feature is that when the boundary value of y = 0 is passed, the relation between the parameter x and the number of carbon atoms in the molecule changes due to an increase in the formal unsaturation (the condition n = x – 1 is replaced by the condition n = x). Therefore, in the latter case, 100 should be subtracted from the iRI homologous increments to compare them with the data for structural analogs of other series. Taking this correction into account, we found that the iRI values for secondary enyne alcohols (12 ± 16) and previously characterized sec-alkynols (23 ± 21) virtually coincide, and for tertiary enyne alcohols, they are consistent with the data for all considered groups of structural analogues (alkanols, alkenols, and alkynols).

Quantitative GC-MS Analysis of Sawdust Bio-Oil

Bio-oils from biomass pyrolysis have a highly promising potential as biofuels or sources of chemicals. The quantitative analysis of bio-oils is quite difficult and requires many standards. In this study, we developed a methodology using only 16 standards for determining the concentration of 49 compounds, representatives of the main chemical classes commons in bio-oils, using relative response factors (RRF) and analytical curves. Five Pinus sawdust bio-oils were analyzed using a GC-MS-DB-5 capillary column (60 m). SCAN mode (from 45 to 450 Daltons) and retention indices (LPTRI) were used for qualitative analysis. For quantitative analysis, SIM mode was preferred, and analytical curves were constructed from an initial solution at 400 mg g-1 of each of the 16 standards, with concentrations ranging from 1 to 150 mg g-1 added to the internal standard (methyl hexanoate) at 70 mg g-1. After the positive identification and quantification of 9 compounds (among the 16 standards used), the other compounds were quantified using the RRF obtained from a standard solution at 30 mg g-1, considering the similarities with those identified standards. 196 compounds were identified, while 49 compounds were quantified, highlighting the monoaromatic hydrocarbons, naphthalenes, benzofurans, alkyl phenols, and catechols.

Clinical evaluation and parental and child satisfaction with restoration of primary teeth using zirconia and stainless steel crowns: A randomised clinical study

Introduction: Full-coronal restoration is the choice of treatment for restoring pulpally treated tooth or tooth with multiple surface involvement. In paediatric dentistry, semi-permanent stainless steel crowns (SSCs) are considered gold standard, but with increasing need of aesthetics, zirconia crowns have started gaining importance. Hence, this study was conducted to evaluate the clinical performance of SSCs and zirconia crowns and to compare the child satisfaction and parental ratings of impact of treatment using these preformed crowns. Materials and Methodology: This study was a part of randomised controlled trial performed on 60 children of 4–8 years old. The primary molars were cemented with either SSCs or zirconia crowns and were evaluated clinically at baseline, 6-month and 12-month follow-up for crown retention, crown fracture, gingival and debris index, wear, marginal integrity and recurrent caries. The trials also evaluated parental satisfaction and child satisfaction based on five-point Likert scale at the end of 12-month follow-up. The data were analysed using Chi-square test for categorical data and independent sample t-test for quantitative data. Results: Both the crowns were 100% retentive at 12-month follow-up. Fair debris score and mild gingivitis were reported in 3% with SSC at 6–12 months. One zirconia crown fractured at 12 months. Fifty-four per cent of parents in zirconia and 57% in SSC stated that the crowns improved masticatory function. Children reported a mean Likert score of 3.0 for SSC and 4.89 for zirconia which was highly significant. Conclusion: Both the crowns increased the overall health of crowned tooth and were fully retentive for the studied duration. However, zirconia crowns were more gingival friendly and had an edge over SSC in terms of aesthetics.

Estimation of uncertainty of measurements of linear retention indices with increasing temperature of the capillary chromatographic column

A brief overview of analysis methods and analytical identification parameters of components of complex mixtures is given. The parameters of identification of substances in the chromatographic analysis of complex multicomponent mixtures – linear retention indices – are considered, and it is shown that to ensure the necessary level of reliability of the analysis results, it is necessary to assess the uncertainty of measuring these indices. A general equation for determining the variance of the result of indirect measurements of linear retention indices is obtained. For the case of the analysis of mixtures containing both assays and n-alkanes, and mixtures with a separate content of these components, its particular formulations are derived from this general equation. A formula for determining the effective number of degrees of freedom of standard uncertainty is presented, taking into account the correlation of input variables in the measurement equation. Mathematical expressions are obtained for calculating the extended uncertainties of estimating linear retention indices, which take into account correlations of retention times of neighboring chromatographic peaks. By methods of interval mathematics, an upper estimate of the standard uncertainty of linear retention indices in the case of the joint presence of analytes and n-alkanes in the analyzed mixture was obtained and its significant decrease in comparison with the specified uncertainty in the analysis of mixtures with a separate content of these components was shown. The correspondence of theoretical and experimental results has been established. The results obtained can be used to identify the components of the analyzed mixture when standardizing chromatographic analysis techniques.

Rapid quantification of 50 fatty acids in small amounts of biological samples for population molecular phenotyping.

Efficient quantification of fatty-acid (FA) composition (fatty-acidome) in biological samples is crucial for understanding physiology and pathophysiology in large population cohorts. Here, we report a rapid GC-FID/MS method for simultaneous quantification of all FAs in numerous biological matrices. Within eight minutes, this method enabled simultaneous quantification of 50 FAs as fatty-acid methyl esters (FAMEs) in femtomole levels following the efficient transformation of FAs in all lipids including FFAs, cholesterol-esters, glycerides, phospholipids and sphingolipids. The method showed satisfactory inter-day and intra-day precision, stability and linearity (R2 > 0.994) within a concentration range of 2-3 orders of magnitude. FAs were then quantified in typical multiple biological matrices including human biofluids (urine, plasma) and cells, animal intestinal content and tissue samples. We also established a quantitative structure-retention relationship (QSRR) for analytes to accurately predict their retention time and aid their reliable identification. We further developed a novel no-additive retention index (NARI) with endogenous FAMEs reducing inter-batch variations to 15 seconds; such NARI performed better than the alkanes-based classical RI, making meta-analysis possible for data obtained from different batches and platforms. Collectively, this provides an inexpensive high-throughput analytical system for quantitative phenotyping of all FAs in 8-minutes multiple biological matrices in large cohort studies of pathophysiological effects.

Comparison of volatile compounds of anal sac secretions between the sexes of domestic dog (Canis lupus familiaris).

Volatile compounds of anal sac secretions are odorant chemicals used across the carnivores for social communication such as identifying individuals and group membership. Odor profiles taken from expressed anal sac secretions of some species of carnivores have been detected in previous studies. In this study, the volatile compounds of anal sac secretions between five male and five female domestic dogs (Canis lupus familiaris) were compared. Volatile chemicals were extracted, separated, and analyzed by gas chromatography-mass spectrometry with solid-phase micro-extraction and identified from their electron ionization mass spectra and Kovats retention indices. The results showed the presence of various types of compounds including organic fatty acids, ketones, aldehydes, esters, and alcohols in the anal sac secretions of dogs. Greater amounts of diversity and esters, and lower amounts of alcohols were detected in the anal sac secretions of females compared to males. This was accompanied by finding citrate and acetic acid ester only in the females. Furthermore, presence of some sex-specific organic compounds like dimethylcyclopentyl ethanone indicates that the volatile profiles of anal sac secretions in 10 domestic dogs are differentiated by host sex.

Composition and Chemical Variability of the Essential Oil from Aerial Parts of Cladanthus scariosus, an Endemic Species to the Moroccan High Atlas.

Cladanthus scariosus (Ball) Oberpr. & Vogt is endemic to Moroccan High Atlas. It is known under the vernacular names Irezghi or Irezgui. Three essential oil samples have been isolated from aerial parts and analyzed by combination of chromatographic and spectroscopic techniques [gas chromatography (GC) in combination with retention indices (RI), gas chromatography-mass spectrometry (GC/MS) and 13 C-NMR spectroscopy]. The compositions of oil samples were dominated by monoterpenes: α-pinene sabinene, and terpinen-4-ol. Chamazulene and dihydrochamazulene isomers as well as various hemiterpene esters and analogs have been identified. To evidence a chemical variability, statistical analysis performed on 13 oil sample compositions allowed partitioning into three groups, mainly differentiated by their contents of sabinene, camphor, borneol, terpinen-4-ol, and germacrene D.

Effect of linear energy density on microstructure and wear resistance of WC-Co-Cr composite coating by laser cladding

To improve the wear resistance of titanium alloy, the WC-reinforced composite coatings were prepared on Ti-6Al-4V substrate by laser cladding. The effect of linear energy density (LED: 73.3 J·mm−1-283.3 J·mm−1) on the microstructure, microhardness and wear resistance of the composite coatings were investigated. The evolution of WC during laser cladding was revealed and discussed. It is found that the WC is dissolved by the forms of releasing W and C with increasing LED, and grows into specific shapes according to the Lifshitz-Slyosov-Wagner model. As the LED increases, the retention index of WC decreases (0.91–0.80) and the grain size increases (1.89 μm–5.81 μm) in the composite coating. The microstructure differences lead to the microhardness and brittleness increasement of composite coating. Compared with the Ti-6Al-4V substrate, the maximum microhardness improvement and wear mass loss reduction are 5 times and 25 times by varying LED. The main wear mechanism of composite coatings is abrasive wear. However, additional forms of wear mass loss such as adhesive wear and WC peeling can occur due to LED variation, and further leads to the difference in wear resistance. It is expected that the evolution of WC, which can regulate the microstructure will provide an effective theoretical foundation for the wear-resistance improvement of the laser cladding coatings.