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Transparent, flexible and conductive thin films of reduced graphene oxide or different types of carbon nanotubes have been prepared through the liquid-liquid interfacial method, and ...deposited over two different substrates, glass or polyethylene terephthalate (PET). Sheet resistance, morphology, transmittance and electrochemical measurements of the films have been evaluated in order to verify potential application as transparent electrodes. The effect of the amount of carbon nanostructures on the properties of the films, as well as the effect of the annealing treatment at different temperatures, has been also evaluated. Results shown that all films can be successfully used as electrodes, presenting optimized sheet resistances ranging from 1.7 to 50kΩ/□ and transmittances at 550nm up to 85 %. Flexible and transparent electrodes presenting high stability have been obtained by the carbon nanostructure films deposited over PET. A modification of the electrodes has been demonstrated, through an electropolymerization of aniline, confirming the potential for further application as flexible devices.
The production of 3D graphene-based materials is an alternative to retain the intrinsic properties of 2D graphene, and improve others like specific surface area, porosity, mechanical properties, etc. ...For practical applications such as electrochemical sensors, the production of electroactive 3D graphene-based composites in one single step with good processability and electrochemical response is extremely desirable. Here, we synthesize 3D composites of crumpled graphene (CG) decorated by copper-based nanoparticles in dry state form without further steps. The aerosol-assisted capillary compression strategy adopted results in copper-based nanoparticles directly connected to CG. The carbon nanostructure controls the nucleation and growth of nanoparticles during capillary compression. We explored the application of the composites as an electrochemical sensor for hydrogen peroxide, and it connects the best performance to the synergism between crumpled graphene and the copper-based nanoparticles.
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•One-step synthesis of 3D crumpled graphene fully decorated by copper-based nanoparticles for an H2O2 electrochemical sensor.•Controlling of the shape of the carbon nanostructure; distribution and size of NP’s; and the electrochemical properties.•H2O2 detection with high sensitivity (0.37 A L mol-1 cm-2) and a low detection limit (0.64 μmol L-1).•Long-term stability for H2O2 detection over 30 days measurements.
Highlights • We describe AUDs among men who have sex with men and trans women in Lima, Peru. • We examine the association between AUDs and high risk sexual behaviors and STIs. • AUDs were not ...associated with either condomless anal intercourse or recent STI. • Interventions to reduce potential harms of alcohol should be context-specific.
Partnership type is an important factor associated with unprotected anal intercourse (UAI) and subsequent risk for HIV and sexually transmitted infections (STI). We examined the association of ...partnership type with UAI among men who have sex with men (MSM) and male-to-female transgender women (TGW) in Lima, Peru, recently diagnosed with HIV and/or STI.
We report data from a cross-sectional analysis of MSM and TGW recently diagnosed with HIV and/or STI in Lima, Peru between 2011 and 2012. We surveyed participants regarding UAI with up to their three most recent sexual partners according to partner type. Multivariable Generalized Estimate Equating (GEE) models with Poisson distribution were used to estimate prevalence ratios (PR) for UAI according to partner type.
Among 339 MSM and TGW recently diagnosed with HIV and/or STI (mean age: 30.6 years, SD 9.0), 65.5% self-identified as homosexual/gay, 16.0% as bisexual, 15.2% as male-to-female transgender, and 3.3% as heterosexual. Participants provided information on 893 recent male or TGW partners with whom they had engaged in insertive or receptive anal intercourse: 28.9% stable partners, 56.4% non-stable/non-transactional partners (i.e. casual or anonymous), and 14.7% transactional partners (i.e. transactional sex client or sex worker). Unprotected anal intercourse was reported with 41.3% of all partners. In multivariable analysis, factors associated with UAI included partnership type (non-stable/non-transactional partner APR 0.73, 95% CI 0.59-0.91, transactional partner APR 0.53 0.36-0.78, p<0.05) and the number of previous sexual encounters with the partner (>10 encounters APR 1.43 1.06-1.92, p<0.05).
UAI was more commonly reported for stable partners and in partnerships with >10 sexual encounters, suggesting UAI is more prevalent in partnerships with a greater degree of interpersonal commitment. Further research assessing partner-level factors and behavior is critical for improving HIV and/or STI prevention efforts among Peruvian MSM and TGW.
Further research is necessary to understand the factors contributing to the high prevalence of HIV/STIs among men who have sex with men (MSM) in Peru. We compared HIV/STI prevalence and risk factors ...between two non-probability samples of MSM, one passively enrolled from an STI clinic and the other actively enrolled from community venues surrounding the clinic in Lima, Peru.
A total of 560 self-identified MSM were enrolled between May-December, 2007. 438 subjects enrolled from a municipal STI clinic and 122 subjects enrolled during community outreach visits. All participants underwent screening for HIV, syphilis, HSV-2, gonorrhoea, and chlamydia and completed a survey assessing their history of HIV/STIs, prior HIV testing, and sexual behavior.
HIV prevalence was significantly higher among MSM enrolled from the clinic, with previously undiagnosed HIV identified in 9.1% compared with 2.6% of community participants. 15.4 % of all MSM screened were infected with ≥ 1 curable STI, 7.4% with early syphilis (RPR ≥ 1:16) and 5.5% with urethral gonorrhoea and/or chlamydia. No significant differences between populations were reported in prevalence of STIs, number of male sex partners, history of unprotected anal intercourse, or alcohol and/or drug use prior to sex. Exchange of sex for money or goods was reported by 33.5% of MSM enrolled from the clinic and 21.2% of MSM from the community (p = 0.01).
Our data demonstrate that the prevalence of HIV and STIs, including syphilis, gonorrhoea, and chlamydia are extremely high among MSM enrolled from both clinic and community venues in urban Peru. New strategies are needed to address differences in HIV/STI epidemiology between clinic- and community-enrolled samples of MSM.
Despite the importance of Eucalyptus spp. in the pulp and paper industry, functional genomic approaches have only recently been applied to understand wood formation in this genus. We attempted to ...establish a global view of gene expression in the juvenile cambial region of Eucalyptus grandis Hill ex Maiden. The expression profile was obtained from serial analysis of gene expression (SAGE) library data produced from 3- and 6-year-old trees. Fourteen-base expressed sequence tags (ESTs) were searched against public Eucalyptus ESTs and annotated with GenBank. Altogether 43,304 tags were generated producing 3066 unigenes with three or more copies each, 445 with a putative identity, 215 with unknown function and 2406 without an EST match. The expression profile of the juvenile cambial region revealed the presence of highly frequent transcripts related to general metabolism and energy metabolism, cellular processes, transport, structural components and information pathways. We made a quantitative analysis of a large number of genes involved in the biosynthesis of cellulose, pectin, hemicellulose and lignin. Our findings provide insight into the expression of functionally related genes involved in juvenile wood formation in young fast-growing E. grandis trees.
New strategies to support partner notification (PN) are critical for STD control and require detailed understanding of how specific individual and partnership characteristics guide notification ...decisions.
From 2011 to 2012, 397 MSM and TW recently diagnosed with HIV, syphilis, or another STD completed a survey on anticipated notification of recent sexual partners and associated factors. Qualitative interviews were conducted with a subset of participants to provide further depth to quantitative findings. Prevalence ratios and generalized estimating equation (GEE) models were used to analyze participant- and partner-level factors associated with anticipated PN.
Among all partners reported, 52.5% were described as "Very Likely" or "Somewhat Likely" to be notified. Anticipated notification was more likely for main partners than casual (adjusted Prevalence Ratio aPR, 95% CI: 0.63, 0.54-0.75) or commercial (aPR, 95% CI: 0.44, 0.31-0.62) partners. Other factors associated with likely notification included perception of the partner as an STD source (aPR, 95% CI: 1.27, 1.10-1.48) and anticipated future sexual contact with the partner (aPR, 95% CI: 1.30, 1.11-1.52). An HIV diagnosis was associated with a lower likelihood of notification than non-HIV STDs (aPR: 0.68, 0.55-0.86). Qualitative discussion of the barriers and incentives to PN reflected a similar differentiation of anticipated notification according to partnership type and type of HIV/STD diagnosis.
Detailed attention to how partnership characteristics guide notification outcomes is essential to the development of new PN strategies. By accurately and thoroughly assessing the diversity of partnership interactions among individuals with HIV/STD, new notification techniques can be tailored to partner-specific circumstances.
We have developed a self-assembly method to obtain multi-wall carbon nanotube films applied in resistive gas sensor devices. This self-assembly method produces a homogeneous multi-wall carbon ...nanotube film with good adhesion to the substrate and an oxygen sensor device with a sensitivity 3.4 times higher than films made by regular casting deposition. A fast recovery time of 0.9s was observed at 160°C operation temperature.
Stigma differentially influences HIV and STI care among MSM, especially regarding partner notification practices. Recognizing the heterogeneous behaviors/identities within the category "MSM," we used ...mixed-methods to assess sexual risk behaviors among men who have sex with men only (MSMO) and behaviorally bisexual MSM (MSMW) with HIV and/or other STIs.
MSMO/MSMW recently diagnosed (< 30 days) with HIV, syphilis, urethritis, or proctitis completed a cross-sectional survey assessing sexual risk behaviors, anticipated disclosure, and sexual partnership characteristics (n = 332). Multivariable generalized estimating equation models assessed characteristics associated with female compared to male partners in the last three partnerships. Follow-up qualitative interviews (n = 30) probed partner-specific experiences (e.g., acts and disclosure).
Among all participants, 13.9% (n = 46) described at least one of their last three sex partners as female (MSMW). MSMW (mean age of 31.8) reported a mean of 3.5 partners (SD = 4.5) in the past 3 months and MSMO (mean age 30.6) reported a mean of 4.6 partners (SD = 9.7) in the past 3 months. MSMW were more likely to report unprotected insertive anal sex (77.9%) than MSMO (43.1%; p < 0.01). Cisgender female partners were associated with condomless insertive sex in the last 3 months (aPR: 3.97, 95%CI: 1.98-8.00) and classification as a "primary" partnership (2.10, 1.34-3.31), and with lower prevalence of recent HIV diagnosis (0.26, 0.11-0.61). Planned notification of HIV/STI diagnoses was less common for female than for male partners (0.52, 0.31-0.85). Narratives illustrate internal (e.g., women as 'true' partners) and community-level processes (e.g., discrimination due to exposure of same-sex behavior) that position homosexual behavior and bisexual identity as divergent processes of deviance and generate vulnerability within sexual networks.
MSMW recently diagnosed with HIV/STI in Peru report varying partnership characteristics, with different partner-specific risk contexts and prevention needs. Descriptions highlight how behaviorally bisexual partnerships cut across traditional risk group boundaries and suggest that HIV/STI prevention strategies must address diverse, partnership-specific risks.
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•PANI/CNT nanocomposites by interfacial polymerization studied using photoemission and AFM.•Presence of neutral and charged species was measured by photoemission.•Incorporation of CNT ...favors the doping level of polyaniline.•C1s core level spectra and AFM present clear evidence of organization of the nanocomposites films.
Photoemission and atomic force microscopy (AFM) studies have been performed on thin films of polyaniline, carbon nanotubes and nanocomposites made of polyaniline (PANI) and carbon nanotubes (CNT) at different CNT/PANI ratios, in order to characterize their chemical states, as well as to investigate their electronic structure and morphology. Photoemission results show the presence of neutral and charged species in the polymer. The presence of charged species increases with the amount of CNT, indicating that the incorporation of CNT favors the doping level of polyaniline. C1s core level spectra present clear evidence of organization of the nanocomposites films as going from PANI aggregates to more aligned CNT. This observation is corroborated by the AFM results.
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