The complex geographical scenario of Mexico allowed the cultural diversification and development of multiple cultures such as Tolteca, Teotihuacan, Mexica, and Maya, among others. Despite this rich cultural heritage, radiometric dating of Mexican cultural samples with radiocarbon (14C) began only in the 1980s and with accelerator mass spectrometry (AMS) in 2013. Analysis of 14C with AMS is the most widely used technique to date archaeological objects and cultural heritage. Since 2013, the Accelerator Mass Spectrometry Laboratory (LEMA) facility of the Institute of Physics at UNAM (IF-UNAM) has supported archaeological research in Mexico, but also investigation in other areas such as geology, physics, chemistry, and environmental sciences through the analysis of 14C, 10Be, 26Al, 129I, and Pu. The absolute dating with 14C continues to be the core of LEMA’s work, where different geographical scenarios of the country and climatic conditions present very diverse analytical challenges. This work presents a basic description of the AMS system of the LEMA laboratory and describes some applications that are currently being developed.

Telomere integrity is influenced by oxidative stress. Also, inflammation-related factors, including nutritional factors, could modulate telomere integrity. The relationship between a posteriori-derived dietary patterns and telomere length (TL) has been scarcely investigated. Thus, our objective was to examine the association between empirically derived dietary patterns ascertained through principal component analysis (PCA) and TL in an older adult Spanish population. A total of 886 older adults (>55 years old; 645 males and 241 females) from the Seguimiento Universidad de Navarra (SUN) cohort were included in the study. TL was measured by monochrome multiplex real-time quantitative PCR. Age-adjusted TL was used for all analyses. Dietary patterns were identified by PCA based on thirty predefined candidate food groups collected from a validated 136-food items frequency questionnaire. Generalised linear models were fitted to obtain β-coefficients and their 95 % CI evaluating differences in TL between each of the four upper quintiles of adherence to dietary patterns and the lowest quintile. Sensitivity analyses by rerunning all multiple linear models under different stratifications were performed to evaluate the robustness of our results. Two major dietary patterns were empirically identified, Western dietary pattern (WDP) and Mediterranean dietary pattern (MDP). After adjustment for potential confounders, longer TL was found among subjects in the highest quintile of MDP (β = 0·064; 95 % CI 0·004, 0·123). The WDP showed no significant association with TL. In conclusion, higher adherence to a posteriori-derived MDP was independently associated with longer telomeres in an older adult Spanish population of the SUN project.

One of the great challenges in the use of nanomaterials is their production at low costs and high yields. In this work aluminum nanoparticles, from aluminum powder, were produced by wet mechanical milling through a combination of different attrition milling conditions such as ball-powder ratio (BPR) and the amount of solvent used. It was observed that at 600 rpm with a BPR of 500/30 g for 12 h, it was possible to produce nanoparticles with a size close to 20 nm, while at 750 rpm with a BPR of 380/12.6 g for 12 h, nanoparticles of approximately 10 nm were obtained. Scanning and transmission electron microscopy confirmed that the milling product is an agglomeration of nanoparticles with different sizes. These results show the feasibility of obtaining aluminum nanoparticles by mechanical milling using only ethanol as solvent, avoiding hazardous by-products obtained from chemical routes, and the use of complicated methods such as laser ablation and arc discharge.

Herein, we report a methodology that leads to the formation of Ru metallic sites, followed by the development and anchorage of Pt-Ru alloyed nanoparticles on the surface of Ordered Mesoporous Hollow Carbon Spheres (OMHCS). Along with the Ru sites, it is demonstrated that the functionalization promotes the formation of functional groups on the surface of the OMHCS. In a first stage, OMHCS are functionalized with the [(η6-C6H5OCH2CH2OH)RuCl2]2 (Ru-dim) and [(η6-C6H4CH(CH3)2CH3)RuCl2]2 (Ru-cym) organometallic compounds. Afterwards, Pt nanoparticles are dispersed by the microwave-assisted polyol method over the functionalized supports obtaining the low-metal content 5 wt. % Pt/OMHCSRu-dim and Pt/OMHCSRu-cym nanocatalysts. The degree of Ru alloyed is found to be around 35%. The low-Pt content Pt/OMHCSRu-cym and Pt/OMHCSRu-dim exhibit a higher catalytic activity for the Oxygen (OER) and the Hydrogen (HER) Evolution Reactions than the Pt/C benchmark and the Pt/OMHCS nanocatalysts. The overpotential for the OER at 10 mA cm-2 (ηOER) is 300 mV and 210 mV smaller at Pt/OMHCSRu-cym and Pt/OMHCSRu-dim compared to Pt/C, respectively. The corresponding values of the HER at -10 mA cm-2 (ηHER) are 14 and 18 mV smaller, respectively. The high catalytic activity of Pt/OMHCSRu-cym and Pt/OMHCSRu-dim has been attributed in part to the presence of Ru0 and RuO2 species from organometallic functionalization, and the modification of the d-valence band of Pt. Their high performance for the OER and the HER opens new lines of research for the design of nanocatalysts for alkaline electrochemical water splitting.

In this work, low-Pt content nanocatalysts (≈ 5 wt. %) supported on Hollow Carbon Spheres (HCS) were synthesized by two routes: i) colloidal conventional polyol, and ii) surfactant-free Bromide Anion Exchange (BAE). The nanocatalysts were labelled as Pt/HCS-P and Pt/HCS-B for polyol and BAE, respectively. The physicochemical characterization of the nanocatalysts showed that by following both methods, a good control of chemical composition was achieved, obtaining in addition well dispersed nanoparticles of less than 3 nm TEM average particle size (d) on the HCS. Pt/HCS-B contained more Pt0 species than Pt/HCS-P, an effect of the synthesis method. In addition, the structure of the HCS remains more ordered after BAE synthesis, compared to polyol. Regarding the catalytic activity for the Oxygen Reduction Reaction (ORR) in 0.5 M KOH, Pt/HCS-P and Pt/HCS-B showed a similar performance in terms of current density (j) at 0.9 V vs. RHE than the benchmark commercial 20 wt. % Pt/C. However, Pt/HCS-P and Pt/HCS-B demonstrated a 6 and 5-fold increase in mass catalytic activity compared to Pt/C, respectively. A positive effect of the high specific surface area of the HCS and its interactions with metal nanoparticles and electrolyte, which promoted the mass transfer, increased the performance of Pt/HCS-P and Pt/HCS-B. The high catalytic activity showed by Pt/HCS-B and Pt/HCS-P for the ORR, even with a low-Pt content, make them promising cathode nanocatalysts for Anion Exchange Membrane Fuel Cells (AEMFC).

Background: Carbapenemase-producing Enterobacteriaceae (CPE) causes infections associated with high mortality rates among hospitalized patients. CPE transmission occurs frequently, and prevention of patient-to-patient transmission is a priority. However, transmission pathways are not yet completely understood. The colonization of the respiratory tract with a CPE may lead to a higher risk of contamination of the patient’s environment increasing the spread of CPE. Objective: We estimated the rate of CPE spread when respiratory tract infection or colonization is present. Methods: We studied CPE dissemination analyzing a cohort of patients admitted between January 2013 and December 2018 at the university hospital complex of A Corua, a tertiary-care hospital. All patients who were hospitalized in the same room as a patient colonized or infected with a CPE (index case) for at least 24 hours were screened for CPE carriage. The microbiological screening was performed with conventional culture or polymerase chain reaction (PCR) to identified possible CPE patient-to-patient transmission. The screening test included several samples: rectal swab, perineal swab, wound or drainage swab, and low respiratory tract sample. Results: Active screening for CPE carriage was performed in 84 contact patients. Men represent 57.1% of the sample, and the mean age was 78.5 years (men, 68.0 years and women, 80.8 years), with significant differences between sexes (12.9; 95% CI, 19.6 to 6.1). The major group of cases (86.9%) were hospitalized in medical wards. Transmission confirmed by PCR occurred in 13 (15.5%) of 84 contact patients, after a mean exposure to the index case of 13.3 days. No significant differences were detected in terms of mean exposure to index cases between those contact patients who result negative and those who result positive. The 35 index cases (41.7%) tested positive for CPE on the respiratory sample, and exposure to them led to 8 positive contact patients (61.5%). Conclusions: CPE transmission in a tertiary-care hospital occurred frequently. The spread rate is even higher when CPE is present at the respiratory level. Understanding the mode of spread is important for designing effective control measures and adding a respiratory sample to CPE screening could be a key consideration.

Funding: None

Disclosures: None

Globally, rock art is one of the most widely distributed manifestations of past human activity. Previous research, however, has tended to focus on the art rather than artists. Understanding which members of society participated in creating such art is crucial to interpreting its social implications and that of the sites at which it is found. This article presents the first application of a method—palaeodermatoglyphics—for the estimation of the sex and age of two later prehistoric individuals who left their fingerprints at the Los Machos rockshelter in southern Iberia. The method has the potential to illuminate the complex socio-cultural dimensions of rock art sites worldwide.

The Mayan Codex of Mexico (MCM), the only Mayan codex found in the 20th century, was unveiled in 1971 during the Ancient Maya Calligraphy exhibition at Club Grolier. The codex comprises 10 pages of bark paper in accordion format, coated with a layer of plaster on both sides. It illustrates the synodic cycles of Venus, with its four phases. Since its discovery, the MCM has been subject to controversy and discussions about its authenticity. In 2016, a group of specialists led by Baltazar Brito chief of the National Library of Anthropology and History, carried out an exhaustive study of the codex with the purpose of determining its temporality and authenticity. In this work, the pre-Columbian authenticity of the codex is verified by the radiocarbon (14C) technique using AMS. Two cleaning procedures were contrasted: the standard acid-base-acid (ABA) protocol and a second one with Soxhlet plus ABA. Results obtained when samples were prepared following ABA protocol only, placed the age of the bark paper between 991 and 1147 cal AD. The second cleaning method with Soxhlet plus ABA, resulted in younger ages, between 1159 and 1261 cal AD. However, we consider that when Sohxlet is used as part of the cleaning protocol, organic contaminants are reduced to a minimum, and 14C dates are more reliable. These results indicate that the vegetal support of the MCM belongs to Postclassical Mayan period and place it as the oldest known manuscript of America found to date.

We present our recent experience with a 6-month-old infant with a personal history of short bowel syndrome that presented with fever, cyanosis, and cardiogenic shock secondary to severe pulmonary hypertension and right ventricular failure without pulmonary thromboembolism. He did not present signs of toxin-mediated disease or Kawasaki disease. He was finally diagnosed with SARS-CoV-2 infection. If this presentation is confirmed in future research, the severe cardiovascular impairment in children with COVID-19 could be also attributable to the primary pulmonary infection, not only to a multisystem inflammatory syndrome but also in children without heart disease.