Infra-Red Active Dirac Plasmon Serie in Potassium Doped-Graphene (KC8) Nanoribbons Array on Al2O3 Substrate.

A theoretical formulation of the electromagnetic response in graphene ribbons on dielectric substrate is derived in the framework of the ab initio method. The formulation is applied to calculate the electromagnetic energy absorption in an array of potassium-doped graphene nanoribbons (KC8-NR) deposited on a dielectric Al2O3 substrate. It is demonstrated that the replacement of the flat KC8 by an array of KC8-NR transforms the Drude tail in the absorption spectra into a series of infrared-active Dirac plasmon resonances. It is also shown that the series of Dirac plasmon resonances, when unfolded across the extended Brillouin zones, resembles the Dirac plasmon. The Dirac plasmon resonances' band structure, within the first Brillouin zone, is calculated. Finally, an excellent agreement between the theoretical absorption and recent experimental results for differential transmission through graphene on an SiO2/Si surface is presented. The theoretically predicted micrometer graphene nanoribbons intercalation compound (GNRIC) in a stage-I-like KC8 is confirmed to be synthesized for Dirac plasmon resonances.

Ataque al personal de la salud durante la pandemia de COVID-19 en Latinoamérica / Attacks on healthcare workers during the COVID-19 pandemic in Latin America

Resumen En la actualidad los profesionales de la salud son el recurso más valioso con el que cuenta cada país para combatir la enfermedad COVID-19. Las tasas de contagio intrahospitalario son altas y ligadas al acto de atención sanitaria. Las medidas de protección por parte de los empleadores son fundamentales para el cuidado de los que cuidan. La situación de pánico generada por el temor a contraer o transmitir la enfermedad, siendo primeros respondedores en la línea de combate ante la pandemia, ha sido amplificada por varios factores. Cuestiones como presión psicológica, carga laboral, mediatización, aspectos judiciales, desprotección, falta de descanso, nuevos roles, discriminación y agresiones son algunas de las situaciones a las que se los profesionales se deben enfrentar.(Acta Med Colomb 2020; 45. DOI:https://doi.org/10.36104/amc.2020.1975).

Abstract Today, healthcare professionals are a country's most valuable resource for combating COVID-19. Hospital contagion rates are high and linked to the practice of health care. Employers' protective measures are essential in caring for the caregivers. The panic resulting from a fear of contracting or transmitting the disease, with first responders being at the front line of the battle against the pandemic, has been amplified by various factors. Issues such as psychological pressure, workload, media coverage, legal aspects, lack of protection, lack of rest, new roles, discrimination and assaults are some of the situations faced by these professionals.(Acta Med Colomb 2020; 45. DOI:https://doi.org/10.36104/amc.2020.1975).

Acremonium mycetoma: a case report and discussion.

Acremonium mycetoma is a rare fungal infection of the skin, tissue, and bones. We present a case of a 64-year-old man with mycetoma due to gardening. The clinical presentation, laboratory findings, and treatment options are reviewed.

Benzo[a]pyrene and its metabolites combined with ultraviolet A synergistically induce 8-hydroxy-2'-deoxyguanosine via reactive oxygen species.

We previously reported that benzo[a]pyrene (BaP) and UVA radiation synergistically induced oxidative DNA damage via 8-hydroxy-2'-deoxyguanosine (8-OHdG) formation in vitro. The present study shows that microsomal BaP metabolites and UVA radiation potently enhance 8-OHdG formation in calf thymus DNA about 3-fold over the parent compound BaP. Utilization of various reactive oxygen species scavengers revealed that singlet oxygen and superoxide radical anion were involved in the 8-OHdG formation induced by microsomal BaP metabolites and UVA. Two specific BaP metabolites, benzo[a]pyrene-r-7,t-8-dihydrodiol-t-9,10-epoxide (+/-) (anti) (BPDE) and BaP-7,8-dione, were further tested for synergism with UVA. BaP-7,8-dione showed an effect on 8-OHdG formation induced by UVA radiation that was similar to that of the parent BaP, whereas BPDE exhibited significantly higher induction of 8-OHdG than BaP. At as low as 0.5 microM, BPDE plus UVA radiation substantially increased 8-OHdG levels about 25-fold over the parent BaP. BPDE increased the formation of 8-OHdG levels in both BPDE concentration- and UVA dose-dependent manners. Additionally, singlet oxygen was found to play a major role in 8-OHdG induction by BPDE and UVA. These results suggest that BaP metabolites such as BPDE synergize with UVA radiation to produce ROS, which in turn induce DNA damage.

Combined subcarcinogenic benzo[a]pyrene and UVA synergistically caused high tumor incidence and mutations in H-ras gene, but not p53, in SKH-1 hairless mouse skin.

Combined subcarcinogenic doses of benzo[a]pyrene (BaP) and UVA induced H-ras, but not p53, gene mutations 8 weeks before tumor emergence in SKH-1 mice. Neither UVA (40 kJ/m2) nor BaP (8 nmol) induced any tumors after mice were topically treated 3 times/week for 25 weeks. However, combined BaP-UVA treatment synergistically increased tumor incidence and multiplicity. All tumors induced by BaP-UVA were malignant. The epidermis was collected from mice treated for 2, 6 and 10 weeks. DNA from UVB- (0.3 kJ/m2) or BaP-UVA-(8 nmol and 40 kJ/m2-induced tumors was isolated and screened for H-ras and p53 mutations. Four types of point mutation, GGC-->GAC, GCC, GTC and CGC, occurred in UVB-induced tumors at H-ras codon 13; and one type of point mutation, GGA-->GAA, at codon 12. Treatment with either BaP alone or BaP-UVA for 10 weeks caused GGA-->GAA mutation at codon 12 or GGC-->GAC mutation at codon 13 in nontumor skin, respectively, as well as in tumors induced by BaP-UVA. All of the 10-week samples treated with either BaP or BaP-UVA showed detectable mutations at codons 12 and 13, but the genetic load was significantly higher in BaP-UVA-treated mice than in those exposed only to BaP. UVA alone induced mutations at codon 12 in only one-third of samples. G-->A mutations induced by BaP or BaP-UVA at position 38 of codon 13 have not been reported previously. C-->T transitions were detected in p53 hot spots of exon 8 in 2 of 19 BaP-UVA-induced tumors but were not found in nontumor skin.