Molecular dynamics simulation of the effects of swift heavy ion irradiation on multilayer graphene and diamond-like carbon

As a promising material used in accelerators and in space in the future, it is important to study the property and structural changes of graphene and diamond-like carbon on the surface as a protective layer before and after swift heavy ion irradiation, although this layer could have a loose structure due to the intrinsic sp(2) surrounding environment of graphene during its deposition period. In this study, by utilizing inelastic thermal spike model and molecular dynamics, we simulated swift heavy ion irradiation and examined the track radius in the vertical direction, as well as temperature, density, and sp(3) fraction distribution along the radius from the irradiation center at different time after irradiation. The temperature in the irradiation center can reach over 11000 K at the beginning of irradiation while there would be a low density and sp(3) fraction area left in the central region after 100 ps. Ring analysis also demonstrated a more chaotic cylindrical region in the center after irradiation. After comprehensive consideration, diamond-like carbon deposited by 70 eV carbon bombardment provided the best protection.Peer reviewe

Homogeneous bilayer graphene film based flexible transparent conductor

Graphene is considered a promising candidate to replace conventional transparent conductors due to its low opacity, high carrier mobility and flexible structure. Multi-layer graphene or stacked single layer graphenes have been investigated in the past but both have their drawbacks. The uniformity of multi-layer graphene is still questionable, and single layer graphene stacks require many transfer processes to achieve sufficiently low sheet resistance. In this work, bilayer graphene film grown with low pressure chemical vapor deposition was used as a transparent conductor for the first time. The technique was demonstrated to be highly efficient in fabricating a conductive and uniform transparent conductor compared to multi-layer or single layer graphene. Four transfers of bilayer graphene yielded a transparent conducting film with a sheet resistance of 180 {\Omega}_{\square} at a transmittance of 83%. In addition, bilayer graphene films transferred onto plastic substrate showed remarkable robustness against bending, with sheet resistance change less than 15% at 2.14% strain, a 20-fold improvement over commercial indium oxide films.Comment: Published in Nanoscale, Nov. 2011 : http://www.rsc.org/nanoscal

Diverging results of areal and volumetric bone mineral density in Down syndrome

Population with Down syndrome (DS) has lower areal BMD, in association with their smaller skeletal size. However, volumetric BMD and other indices of bone microarchitecture, such as trabecular bone score (TBS) and calcaneal ultrasound (QUS), were normal. INTRODUCTION: Patients with DS have a number of risk factors that could predispose them to osteoporosis. Several studies reported that people with DS also have lower areal bone mineral density, but differences in the skeletal size could bias the analysis. METHODS: Seventy-five patients with DS and 76 controls without intellectual disability were recruited. Controls were matched for age and sex. Bone mineral density (BMD) was measure by Dual-energy X-ray Absorptiometry (DXA), and volumetric bone mineral density (vBMD) was calculated by published formulas. Body composition was also measured by DXA. Microarchitecture was measured by TBS and QUS. Serum 25-hidroxyvitamin D (25OHD), parathyroid hormone (PTH), aminoterminal propeptide of type collagen (P1NP), and C-terminal telopeptide of type I collagen (CTX) were also determined. Physical activity was assessed by the International Physical Activity Questionnaires (IPAQ-short form). To evaluate nutritional intake, we recorded three consecutive days of food. RESULTS: DS individuals had lower height (151 ± 11 vs. 169 ± 9 cm). BMD was higher in the controls (lumbar spine (LS) 0.903 ± 0.124 g/cm2 in patients and 0.997 ± 0.115 g/cm2 in the controls; femoral neck (FN) 0.761 ± .126 g/cm2 and 0.838 ± 0.115 g/cm2, respectively). vBMD was similar in the DS group (LS 0.244 ± 0.124 g/cm3; FN 0.325 ± .0.073 g/cm3) and the controls (LS 0.255 ± 0.033 g/cm3; FN 0.309 ± 0.043 g/cm3). Microarchitecture measured by QUS was slightly better in DS, and TBS measures were similar in both groups. 25OHD, PTH, and CTX were similar in both groups. P1NP was higher in the DS group. Time spent on exercise was similar in both groups, but intensity was higher in the control group. Population with DS has correct nutrition. CONCLUSIONS: Areal BMD is reduced in DS, but it seems to be related to the smaller body and skeletal size. In fact, the estimated volumetric BMD is similar in patients with DS and in control individuals. Furthermore, people with DS have normal bone microarchitecture

Flexible Indium-Tin Oxide Crystal on Plastic Substrates Supported by Graphene Monolayer

Flexible and crystallized indium-tin oxide (ITO) thin films were successfully obtained on plastic polyethylene terephthalate (PET) films with monolayered graphene as a platform. The highly crystalline ITO (c-ITO) was first fabricated on a rigid substrate of graphene on copper foil and it was subsequently transferred onto a PET substrate by a well-established technique. Despite the plasma damage during ITO deposition, the graphene layer effectively acted as a Cu-diffusion barrier. The c-ITO/graphene/ PET electrode with the 60-nm-thick ITO exhibited a reasonable sheet resistance of similar to 45 Omega sq(-1) and a transmittance of similar to 92% at a wavelength of 550 nm. The c-ITO on the monolayered graphene support showed significant enhancement in flexibility compared with the ITO/PET film without graphene because the atomically controlled monolayered graphene acted as a mechanically robust support. The prepared flexible transparent c-ITO/graphene/PET electrode was applied as the anode in a bulk heterojunction polymer solar cell (PSC) to evaluate its performance, which was comparable with that of the commonly used c-ITO/glass electrode. These results represent important progress in the fabrication of flexible transparent electrodes for future optoelectronics applications

High‐Volume Processed, ITO‐Free Superstrates and Substrates for Roll‐to‐Roll Development of Organic Electronics

The fabrication of substrates and superstrates prepared by scalable roll‐to‐roll methods is reviewed. The substrates and superstrates that act as the flexible carrier for the processing of functional organic electronic devices are an essential component, and proposals are made about how the general availability of various forms of these materials is needed to accelerate the development of the field of organic electronics. The initial development of the replacement of indium‐tin‐oxide (ITO) for the flexible carrier materials is described and a description of how roll‐to‐roll processing development led to simplification from an initially complex make‐up to higher performing materials through a more simple process is also presented. This process intensification through process simplification is viewed as a central strategy for upscaling, increasing throughput, performance, and cost reduction

Choice of the initial antiretroviral treatment for HIV-positive individuals in the era of integrase inhibitors

BACKGROUND: We aimed to describe the most frequently prescribed initial antiretroviral therapy (ART) regimens in recent years in HIV-positive persons in the Cohort of the Spanish HIV/AIDS Research Network (CoRIS) and to investigate factors associated with the choice of each regimen. METHODS: We analyzed initial ART regimens prescribed in adults participating in CoRIS from 2014 to 2017. Only regimens prescribed in >5% of patients were considered. We used multivariable multinomial regression to estimate Relative Risk Ratios (RRRs) for the association between sociodemographic and clinical characteristics and the choice of the initial regimen. RESULTS: Among 2874 participants, abacavir(ABC)/lamivudine(3TC)/dolutegavir(DTG) was the most frequently prescribed regimen (32.1%), followed by tenofovir disoproxil fumarate (TDF)/emtricitabine (FTC)/elvitegravir(EVG)/cobicistat(COBI) (14.9%), TDF/FTC/rilpivirine (RPV) (14.0%), tenofovir alafenamide (TAF)/FTC/EVG/COBI (13.7%), TDF/FTC+DTG (10.0%), TDF/FTC+darunavir/ritonavir or darunavir/cobicistat (bDRV) (9.8%) and TDF/FTC+raltegravir (RAL) (5.6%). Compared with ABC/3TC/DTG, starting TDF/FTC/RPV was less likely in patients with CD4100.000 copies/mL. TDF/FTC+DTG was more frequent in those with CD4100.000 copies/mL. TDF/FTC+RAL and TDF/FTC+bDRV were also more frequent among patients with CD4<200 cells//muL and with transmission categories other than men who have sex with men. Compared with ABC/3TC/DTG, the prescription of other initial ART regimens decreased from 2014-2015 to 2016-2017 with the exception of TDF/FTC+DTG. Differences in the choice of the initial ART regimen were observed by hospitals' location. CONCLUSIONS: The choice of initial ART regimens is consistent with Spanish guidelines' recommendations, but is also clearly influenced by physician's perception based on patient's clinical and sociodemographic variables and by the prescribing hospital location