Evaluated electron scattering cross section dataset for gaseous benzene in the energy range 0.1-1000 eV

In this study, a complete and self-consistent cross section dataset for electron transport simulations through gaseous benzene in the energy range 0.1-1000 eV has been critically compiled. Its reliability has been evaluated through a joint experimental and computational procedure. To accomplish this, the compiled dataset has been used as input for event-by-event Monte Carlo simulations of the magnetically confined electron transport through gaseous benzene, and the simulated transmitted intensity has been compared with the experimental one for different incident energies and benzene gas pressures.

A comparison of experimental and theoretical low energy positron scattering from furan

This paper presents a joint experimental and theoretical study of positron scattering from furan. Experimental data were measured using the low energy positron beamline located at the Australian National University and cover an energy range from 1 eV to 30 eV. Cross sections were measured for total scattering, total elastic and inelastic scattering, positronium formation, and differential elastic scattering. Two theoretical approaches are presented: the Schwinger multichannel method and the independent atom method with screening corrected additivity rule. In addition, our data are compared to corresponding electron scattering results from the same target with a number of significant differences observed and discussed.

THU0001 GENOME-WIDE ASSOCIATION STUDY ON JOINT EROSIONS IN RHEUMATOID ARTHRITIS SUPPORTS DIFFERENTIAL PATHOLOGICAL MECHANISMS ACCORDING TO ANTI-CCP STATUS

Background:

Joint damage is the pathological hallmark of rheumatoid arthritis (RA). To identify the genetic variation associated with a higher level of erosions has proven elusive.

Objectives:

The objective of the present study was to perform a genome-wide association study on joint damage in a cohort of RA patients of the Spanish population. Our aims were to provide independent validation of previously reported variants and to identify new candidate risk loci. A stratified analysis was performed based on positivity to ACPA status.

Methods:

A total of 1,135 patients diagnosed with RA using the ACR-EULAR criteria recruited by the IMID Consortium were genotyped using a 550,000 single-nucleotide polymorphism array. Additional SNPs were imputed using the 1KG genome data. Joint damage was performed using the S-score, a simplified radiographic erosion score that has a high correlation with the Sharp-van der Hejde score (1). Association testing of SNPs with joint damage was performed via linear regression with the addition of the years of evolution as covariate. The two main components of genetic variation were also added to adjust for potential population stratification. A total of 50 SNPs representing previously reported loci associated with joint damage were selected. Genetic association was also performed at the pathway level using Pascal.

Results:

45 out of 50 SNPs representing 31 previously reported loci for joint damage could be satisfactorily imputed. Association testing of the whole patient cohort replicated the association withIL2RAandTRAF1. Of relevance, after stratifying for anti-CCP five new loci were replicated:KIF5AandSOSTin ACPA-positive RA andCD40, DKK1andTNFin ACPA-negative RA.IL2RAwas only significant in the ACPA-positive group andTRAF1was not significant in either strata. GWAS on the ACPA-positive cohort and on the ACPA-negative group identified n=7 and n=18 loci with P-values < 1x10-5, respectively. From these, however, only 1 SNP showed nominal significant association in the other patient group. Based on this evidence, we performed a pathway-based analysis to understand the biological mechanisms underlying this difference. Pathway analysis showed 52 biological processes associated with joint damage in ACPA-negative RA and 32 pathways in the ACPA-positive group, with only two shared biological processes between the two groups. Fc Gamma receptor mediated phagocytosis was the topmost biological process associated with erosions specifically in ACPA-negative RA and Signalling by Fibroblast Growth Factor mutants was the top process specific for ACPA-positive patients.

Conclusion:

The results from our study provide suggestive evidence that the genetic basis for joint damage is different according to the presence of ACPA. Replication of the new candidate loci in an independent patient cohort is underway.

References:

[1]Lopez-Lasanta, M., Julià, A., Maymó, J., Fernández-Gutierrez, B., Ureña-Garnica, I., Blanco, F. J., ... & Tornero, J. (2015). Variation at interleukin-6 receptor gene is associated to joint damage in rheumatoid arthritis.Arthritis research & therapy,17(1), 242.

Disclosure of Interests:

Antonio Julià: None declared, Francisco Blanco: None declared, Benjamin Fernandez: None declared, Antonio Gonzalez: None declared, Juan D: None declared, Joan Maymó: None declared, Mercedes Alperi-López: None declared, Alejandro Olive: None declared, Héctor Corominas Speakers bureau: Abbvie, Lilly, Pfizer, Roche, Victor Martinez Taboada: None declared, Isidoro González-Álvaro Grant/research support from: Roche Laboratories, Consultant of: Lilly, Sanofi, Paid instructor for: Lilly, Speakers bureau: Abbvie, MSD, Roche, Lilly, Antonio Fernandez-Nebro: None declared, Alba Erra: None declared, Simon Sánchez Fernandez: None declared, Núria Palau: None declared, Maria Lopez Lasanta: None declared, Adrià Aterido: None declared, Jesús Tornero: None declared, Sara Marsal: None declared

SAT0006 SIMULTANEOUS ANALYSIS OF ANTI-CCP, RHEUMATOID FACTOR, ANTI-PAD4 AND ANTI-CARBAMYLATED PROTEIN ANTIBODIES REVEALS INTERACTION EFFECTS WITH RESPONSE TO ANTI-TNF THERAPY IN RHEUMATOID ARTHRITIS

Background:

Blocking of the Tumor Necrosis Factor (TNF) activity is a successful therapeutic approach for 2 out of 3 Rheumatoid Arthritis patients. Identifying the patients that will not respond to this therapeutic approach is a major translational goal in RA. Association of seropositivity to rheumatoid factor (RF) or anti-cyclic-citrullinated antibodies (anti-CCP) with anti-TNF response has proven inconclusive, suggesting that other yet unexplored biomarkers could be more informative for this goal.

Objectives:

We tested the association of two recently introduced biomarkers in RA: anti-carbamylated protein antibodies (anti-CarP) and anti-peptidylarginine deiminase type 4 (anti-PAD4).

Methods:

A prospective cohort of n=80 RA patients starting anti-TNF therapy was recruited and levels for all four autoantibodies -RF, anti-CCP, anti-CarP and anti-PAD4- were measured at baseline. The change in DAS28 score between baseline and week 12 of therapy was used as the clinical endpoint.

Results:

Single marker-analysis showed no significant association with drug response. However, when testing for interactions between autoantibodies, we found highly significant associations with drug response. Anti-CCP and RF showed a positive interaction with the response to anti-TNF therapy (P=0.00068), and anti-PAD4 and antiCarP titers showed a negative interaction with the clinical response at week 12 (P=0.0062). Using an independent retrospective sample (n=199 patients), we validated the interaction between anti-CCP and RF with the clinical response to anti-TNF agents. (P=0.044).

Conclusion:

The results of this study show that interactions between antibodies are important in the response to anti-TNF therapy and suggest potential pathogenic relationships.

Acknowledgments :

We would like to thank the clinical researchers and patients participating in the IMID Consortium for their collaboration

Disclosure of Interests:

Antonio Julià: None declared, Maria Lopez Lasanta: None declared, Francisco Blanco: None declared, Antonio Gómez: None declared, Isabel Haro: None declared, Antonio Juan Mas: None declared, Alba Erra: None declared, Mª Luz García Vivar: None declared, Jordi Monfort: None declared, Simon Sánchez Fernandez: None declared, Isidoro González-Álvaro Grant/research support from: Roche Laboratories, Consultant of: Lilly, Sanofi, Paid instructor for: Lilly, Speakers bureau: Abbvie, MSD, Roche, Lilly, Mercedes Alperi-López: None declared, Raúl Castellanos: None declared, Antonio Fernandez-Nebro: None declared, Cesar Diaz Torne: None declared, Núria Palau: None declared, Raquel M Lastra: None declared, Jordi Lladós: None declared, Raimon Sanmarti: None declared, Sara Marsal: None declared

Electron scattering cross sections from nitrobenzene in the energy range 0.4-1000 eV: the role of dipole interactions in measurements and calculations

Absolute total electron scattering cross sections (TCS) for nitrobenzene molecules with impact energies from 0.4 to 1000 eV have been measured by means of two different electron-transmission experimental arrangements. For the lower energies (0.4-250 eV) a magnetically confined electron beam system has been used, while for energies above 100 eV a linear beam transmission technique with high angular resolution allowed accurate measurements up to 1000 eV impact energy. In both cases random uncertainties were maintained below 5-8%. Systematic errors arising from the angular and energy resolution limits of each apparatus are analysed in detail and quantified with the help of our theoretical calculations. Differential elastic and integral elastic, excitation and ionisation as well as momentum transfer cross sections have been calculated, for the whole energy range considered here, by using an independent atom model in combination with the screening corrected additivity rule method including interference effects (IAM-SCARI). Due to the significant permanent dipole moment of nitrobenzene, additional differential and integral rotational excitation cross sections have been calculated in the framework of the Born approximation. If we ignore the rotational excitations, our calculated total cross section agrees well with our experimental results for impact energies above 15 eV. Additionally, they overlap at 10 eV with the low energy Schwinger Multichannel method with Pseudo Potentials (SMCPP) calculation available in the literature (L. S. Maioli and M. H. F. Bettega, J. Chem. Phys., 2017, 147, 164305). We find a broad feature in the experimental TCS at around 1.0 eV, which has been related to the formation of the NO2- anion and assigned to the π*(b1) resonance, according to previous mass spectra available in the literature. Other local maxima in the TCSs are found at 4.0 ± 0.2 and 5.0 ± 0.2 eV and are assigned to core excited resonances leading to the formation of the NO2- and O2- anions, respectively. Finally, for energies below 10 eV, differences found between the present measurements, the SMCPP calculation and our previous data for non-polar benzene have revealed the importance of accurately calculating the rotational excitation contribution to the TCS before comparing theoretical and experimental data. This comparison suggests that our dipole-Born calculation for nitrobenzene overestimates the magnitude of the rotational excitation cross sections below 10 eV.

Experimental and theoretical analysis for total electron scattering cross sections of benzene

Measurements of the total electron scattering cross sections (TCSs) from benzene, in the impact energy range of 1-1000 eV, are presented here by combining two different experimental systems. The first utilizes a magnetically confined electron transmission beam for the lower energies (1-300 eV), while the second utilizes a linear transmission beam apparatus for the higher energies (100-1000 eV). These cross sections have also been calculated by means of two different theoretical methods, the Schwinger Multichannel with Pseudo Potential (SMCPP) procedure, employing two different approaches to account for the polarization of the target for impact energies between 0.1 and 15 eV, and the Independent Atom Model with the Screening Corrected Additivity Rule including Interference effect (IAM-SCAR+I) paradigm to cover the 10-10 000 eV impact energy range. The present results are compared with available theoretical and experimental data, with the level of accord being good in some cases and less satisfactory in others, and some predicted resonances have been identified. In particular, we found a π^* shape resonance at 1.4 eV and another feature in the energy region 4.6-4.9 eV interpreted as a π^* resonance (²B_2g symmetry), which is a mixture of shape and a core excited resonance, as well as a Feshbach resonance at 5.87 eV associated with the 3s (a_1g) Rydberg state. A Born-type formula to extrapolate TCS values for energies above 10 000 eV is also given. This study provides a complete set of TCS data, with uncertainty limits within 10%, ready to be used for modeling electron transport applications.

Electron scattering from 1-butanol at intermediate impact energies: Total cross sections

We report experimental measurements of the absolute total cross sections (TCSs) for electron scattering from 1-butanol at impact energies in the range 80-400 eV. Those measurements were conducted by considering the attenuation of a collimated electron beam, at a given energy, through a gas cell containing 1-butanol, at a given pressure, and through application of the Beer-Lambert law to derive the required TCS. We also report theoretical results using the Independent-Atom Model with Screening Corrected Additivity Rule and Interference approach. Those results include the TCS, the elastic integral cross section (ICS), the ionization total ICS, and the sum over all excitation process ICSs with agreement at the TCS level between our measured and calculated results being encouraging.

Total cross section measurements for electron scattering from dichloromethane

Using our magnetically confined electron transmission apparatus, we report the results of total cross sections (TCSs) for electron scattering from dichloromethane (CH₂Cl₂). The energy range of this study is 1-300 eV. Wherever possible, the present data are compared to earlier measured TCSs of Wan et al. [J. Chem. Phys. 94, 1865 (1991)] and Karwasz et al. [Phys. Rev. A 59, 1341 (1999)] and to the corresponding theoretical independent atom model with screening corrected additivity rule and interference term (IAM-SCAR+I) results of Krupa et al. [Phys. Rev. A 97, 042702 (2018)] and a spherical complex optical potential formulation calculation of Naghma et al. [J. Electron Spectrosc. Relat. Phenom. 193, 48 (2014)]. Within their respective uncertainties, the present TCS and those of Karwasz et al. are found to be in very good agreement over their common energy range. However, agreement with the results of Wan et al. is quite poor. The importance of the experimentally inherent 'missing angle' effect (see later) on the measured TCS is investigated and found to be significant at the lower energies studied. Indeed, when this effect is accounted for, agreement between our measured TCSs and the corrected IAM-SCAR+I+rotations calculation results are, for energies above about 3 eV, in good accord (to better than 8%). Finally, we observe two σ ^* shape resonances, consistent with the earlier electron transmission spectroscopy results of Burrow et al. [J. Chem. Phys. 77, 2699 (1982)], at about 2.8 eV and 4.4 eV incident electron energy, in our measured TCS.

Incident hand OA is strongly associated with reduced peripheral blood leukocyte telomere length

OBJECTIVE

To evaluate the relationship of telomere length to the prevalence and incidence of hand osteoarthritis in a longitudinal cohort.

DESIGN

We conducted a cross-sectional and longitudinal analysis of data from a subset of participants in the Osteoarthritis Initiative (OAI) recruited between February 2004 and May 2006. 274 individuals were eligible for the study based on availability of both baseline and 48-month hand radiographs and peripheral blood leucocyte telomere length data. Mean telomere length of peripheral blood leukocytes (PBL)s from the DNA samples was determined using a validated quantitative polymerase chain reaction (PCR)-based assay, and hand radiographs were analyzed and graded using the Kellgren-Lawrence scale.

RESULTS

In joint -level analyses, prevalent Interphalangeal Joint Osteoarthritis (IPJOA) was significantly associated with PBL telomere length in the baseline sample in unadjusted analyses (RR = 2.84; 95% CI:0.87-9.29) or in models adjusted for age, sex, and body mass index (aRR = 1.10; 95% CI: 0.96-1.27). The association in crude and adjusted analyses appeared slightly stronger with incident IPJOA, especially in the subset with normal hands at baseline (aRR = 1.62; 95% CI: 1.02-2.57). PBL telomere length was also associated with prevalent HOA at baseline (significant in unadjusted analysis: RR = 1.22; 95% CI 1.06-1.42), but not after adjusting for covariates: aRR = 1.12; 95% CI: 0.96-1.30). The magnitude of association was stronger for incident HOA, especially incident symptomatic HOA (aRR = 1.53; 95% CI: 1.09-2.15).

CONCLUSIONS

In summary, the results of this exploratory analysis are confirmatory of previous work showing a cross-sectional relationship between telomere length and HOA and add to the field by demonstrating an even stronger association with incident IPJOA, both radiographic and symptomatic.

Total electron scattering cross sections from para-benzoquinone in the energy range 1-200 eV

Total electron scattering cross sections, from para-benzoquinone, for impact energies ranging between 1 to 200 eV, have been obtained by measuring the attenuation of a linear electron beam under magnetic confinement conditions. Random uncertainty limits on these values have been found to be within 5%. Systematic errors, due to the axial magnetic beam conditions in combination with the acceptance angle of the detector, have been evaluated by integrating our calculated independent atom model with the screening corrected additivity rule and interference term elastic differential cross sections over that detection acceptance angle. Our previous calculations and measurements on this molecule (Jones et al., J. Chem. Phys., 2018, 148, 124312 and J. Chem. Phys., 2018, 148, 204305), have been compiled and complemented with new elastic and inelastic scattering cross section calculations in order to obtain a comprehensive cross section data base, within the considered energy range, for modelling purposes. The self-consistency of the present data set has been evaluated by simulating the electron transport of 15 eV electrons in para-benzoquinone, and comparing those results with the observed transmitted intensity distribution.

Magnetically confined electron beam system for high resolution electron transmission-beam experiments

A novel experimental setup has been implemented to provide accurate electron scattering cross sections from molecules at low and intermediate impact energies (1-300 eV) by measuring the attenuation of a magnetically confined linear electron beam from a molecular target. High-resolution electron energy is achieved through confinement in a magnetic gas trap where electrons are cooled by successive collisions with N₂. Additionally, we developed and present a method to correct systematic errors arising from energy and angular resolution limitations. The accuracy of the entire measurement procedure is validated by comparing the N₂ total scattering cross section in the considered energy range with benchmark values available in the literature.

A process to describe radiation damage at the molecular level. Application to the 125I seeds in water

The correlation between the absorbed energy and the induced biological damage still has unclear aspects, especially in the low energy and low dose rate irradiation regimes. From the knowledge of the molecular-induced effects (dissociations), it would be possible to better understand the side effects of radiation, such as induced cancers or damage to healthy tissue. With this in view, this paper presents results of a simulation of a ¹²⁵I-seed treatment with an event-by-event MC code (LEPTS) specifically designed to account for the low energy secondary particle interactions, such as electron attachment, vibro-rotational and neutral dissociation interactions. This calculation allowed us to analyze the potential radiation damage not only in connection with the energy deposition, but also in terms of induced molecular dissociations by taking into account ionizing and non-ionizing dissociative processes. We propose that this description of the molecular level damage be the basis for nanodosimetric evaluations.

Total cross sections for electron scattering by 1-propanol at impact energies in the range 40-500 eV

Absolute total cross section (TCS) measurements for electron scattering from 1-propanol molecules are reported for impact energies from 40 to 500 eV. These measurements were obtained using a new apparatus developed at Juiz de Fora Federal University-Brazil, which is based on the measurement of the attenuation of a collimated electron beam through a gas cell containing the molecules to be studied at a given pressure. Besides these experimental measurements, we have also calculated TCS using the Independent-Atom Model with Screening Corrected Additivity Rule and Interference (IAM-SCAR+I) approach with the level of agreement between them being typically found to be very good.

Genotypic tropism testing of proviral DNA to guide maraviroc initiation in aviraemic subjects: 48-week analysis of results from the PROTEST study

OBJECTIVES

Maraviroc (MVC) is a suitable drug for aviraemic subjects on antiretroviral treatment (ART) developing toxicity. Its prescription requires prior tropism testing. It is unknown if proviral DNA genotypic tropism testing is reliable for guiding MVC initiation in aviraemic subjects, so this study was carried out to address this issue.

METHODS

PROTEST was a phase 4, prospective, single-arm clinical trial carried out in 24 HIV care centres in Spain. MVC-naïve HIV-1-infected patients with HIV-1 RNA < 50 copies/mL on stable ART during the previous 6 months who required an ART change because of toxicity and who had R5 HIV, as determined by proviral DNA genotypic tropism testing, initiated MVC with two nucleoside reverse transcriptase inhibitors (NRTIs) and were followed for 48 weeks. Virological failure was defined as two consecutive viral load measurements > 50 copies/mL.

RESULTS

Tropism results were available for 141 of 175 (80.6%) subjects screened: 60% had R5 and 85% of these (n = 74) were finally included in the study. Previous ART included protease inhibitors (PIs) in 62% of subjects, nonnucleoside reverse transcriptase inhibitors (NNRTIs) in 36%, and integrase inhibitors (INIs) in 2%. Main reasons for treatment change were dyslipidaemia (42%), gastrointestinal symptoms (22%) and liver toxicity (15%). MVC was given alongside tenofovir (TDF)/emtricitabine (FTC) (54%) and abacavir (ABC)/lamivudine (3TC) (40%) in most patients. Eighty-four per cent of patients maintained a viral load < 50 copies/mL to week 48, whereas 16% discontinued treatment: two withdrew informed consent, one had an R5 to X4 shift between screening and baseline, one was lost to follow-up, one developed an adverse event (rash), two died from non-study-related causes, and five developed protocol-defined virological failure.

CONCLUSIONS

Initiation of MVC plus two NRTIs in aviraemic subjects based on genotypic tropism testing of proviral HIV-1 DNA is associated with low rates of virological failure for up to 1 year.

GPRC5A is a potential oncogene in pancreatic ductal adenocarcinoma cells that is upregulated by gemcitabine with help from HuR

GPRC5A is an orphan G-protein coupled receptor with an intriguing dual behavior, acting as an oncogene in some cancers and as a tumor suppressor in other cancers. In the pancreatic cancer context, very little is known about GPRC5A. By analyzing messenger RNA (mRNA) expression data from 675 human cancer cell lines and 10 609 samples from The Cancer Genome Atlas (TCGA) we found that GPRC5A's abundance in pancreatic cancer is highest (cell lines) or second highest (TCGA) among all tissues and cancer types. Further analyses of an independent set of 252 pancreatic normal and cancer samples showed GPRC5A mRNA to be more than twofold upregulated in primary tumor samples compared with normal pancreas (P-value<10⁻⁵), and even further upregulated in pancreatic cancer metastases to various organs (P-value=0.0021). Immunostaining of 208 cores (103 samples) of a tissue microarray showed generally low expression of GPRC5A protein in normal pancreatic ductal cells; on the other hand, in primary and metastatic samples, GPRC5A protein levels were dramatically increased in pancreatic ductal cells. In vitro studies of multiple pancreatic cancer cell lines showed that an increase in GPRC5A protein levels promoted pancreatic cancer cell growth and migration. Unexpectedly, when we treated pancreatic cancer cell lines with gemcitabine (2′,2′-difluorodeoxycytidine), we observed an increase in GPRC5A protein abundance. On the other hand, when we knocked down GPRC5A we sensitized pancreatic cancer cells to gemcitabine. Through further experimentation we showed that the monotonic increase in GPRC5A protein levels that we observe for the first 18 h following gemcitabine treatment results from interactions between GPRC5A's mRNA and the RNA-binding protein HuR, which is an established key mediator of gemcitabine's efficacy in cancer cells. As we discovered, the interaction between GPRC5A and HuR is mediated by at least one HuR-binding site in GPRC5A's mRNA. Our findings indicate that GPRC5A is part of a complex molecular axis that involves gemcitabine and HuR, and, possibly, other genes. Further work is warranted before it can be established unequivocally that GPRC5A is an oncogene in the pancreatic cancer context.

Experimental and theoretical cross sections for positron scattering from the pentane isomers

Isomerism is ubiquitous in chemistry, physics, and biology. In atomic and molecular physics, in particular, isomer effects are well known in electron-impact phenomena; however, very little is known for positron collisions. Here we report on a set of experimental and theoretical cross sections for low-energy positron scattering from the three structural isomers of pentane: normal-pentane, isopentane, and neopentane. Total cross sections for positron scattering from normal-pentane and isopentane were measured at the University of Trento at incident energies between 0.1 and 50 eV. Calculations of the total cross sections, integral cross sections for elastic scattering, positronium formation, and electronic excitations plus direct ionization, as well as elastic differential cross sections were computed for all three isomers between 1 and 1000 eV using the independent atom model with screening corrected additivity rule. No definitive evidence of a significant isomer effect in positron scattering from the pentane isomers appears to be present.

Glutaminase 2 is a novel negative regulator of small GTPase Rac1 and mediates p53 function in suppressing metastasis

Glutaminase (GLS) isoenzymes GLS1 and GLS2 are key enzymes for glutamine metabolism. Interestingly, GLS1 and GLS2 display contrasting functions in tumorigenesis with elusive mechanism; GLS1 promotes tumorigenesis, whereas GLS2 exhibits a tumor-suppressive function. In this study, we found that GLS2 but not GLS1 binds to small GTPase Rac1 and inhibits its interaction with Rac1 activators guanine-nucleotide exchange factors, which in turn inhibits Rac1 to suppress cancer metastasis. This function of GLS2 is independent of GLS2 glutaminase activity. Furthermore, decreased GLS2 expression is associated with enhanced metastasis in human cancer. As a p53 target, GLS2 mediates p53's function in metastasis suppression through inhibiting Rac1. In summary, our results reveal that GLS2 is a novel negative regulator of Rac1, and uncover a novel function and mechanism whereby GLS2 suppresses metastasis. Our results also elucidate a novel mechanism that contributes to the contrasting functions of GLS1 and GLS2 in tumorigenesis.

Limnological and ecological methods: approaches, and sampling strategies for middle Xingu River in the area of influence of future Belo Monte Power Plant

In this paper the authors describe the limnological approaches, the sampling methodology, and strategy adopted in the study of the Xingu River in the area of influence of future Belo Monte Power Plant. The river ecosystems are characterized by unidirectional current, highly variable in time depending on the climatic situation the drainage pattern an hydrological cycle. Continuous vertical mixing with currents and turbulence, are characteristic of these ecosystems. All these basic mechanisms were taken into consideration in the sampling strategy and field work carried out in the Xingu River Basin, upstream and downstream the future Belo Monte Power Plant Units.

Excitation of vibrational quanta in furfural by intermediate-energy electrons

We report cross sections for electron-impact excitation of vibrational quanta in furfural, at intermediate incident electron energies (20, 30, and 40 eV). The present differential cross sections are measured over the scattered electron angular range 10°-90°, with corresponding integral cross sections subsequently being determined. Furfural is a viable plant-derived alternative to petrochemicals, being produced via low-temperature plasma treatment of biomass. Current yields, however, need to be significantly improved, possibly through modelling, with the present cross sections being an important component of such simulations. To the best of our knowledge, there are no other cross sections for vibrational excitation of furfural available in the literature, so the present data are valuable for this important molecule.