Estudio comparativo de técnicas de preparación de muestraspara microscopía electrónica de transmisión de recubrimientos cerámicos proyectados por plasma

The development of advanced materials, with complex microstructures, is a permanent challenge to the development and application of new efficient techniques for microstructural characterization. In ceramic coatings on metals, there exist a differential ion-milling ratio between both components, limiting in principle the use of conventional techniques. In this work, we report on a comparative study of TEM sample preparation techniques for plasma-sprayed ceramic coatings. Firstly, we have used a procedure derived from the conventional one (polishing, dimpling, ion milling), and alternatively a new technique using focused ion-beam milling. The material selected for this study is fine-grained alumina that was plasma-sprayed on a steel substrate. The efficiency of both techniques is discussed along with the most significant microstructural features of the material subject of study

USE OF MORINGA SEED (Moringa oleifera Lam.) AS A BIOCOAGULANT TO IMPROVE SURFACE WATER QUALITY

Using Moringa oleifera (Moringa oleifera Lam.) seed as a biocoagulant to enhance surface water's physical and chemical quality was the goal of this study. The methodology applied for the generation of experimental data was through the use of the Jar Test equipment, in a dose of 40 mg/L to 140 mg/L, then a fast mixing of 100 rpm for 1 minute and a slow mixing of 40 rpm for 10 minutes was performed, and sedimentation was left for 5 to 30 minutes, with 5 minutes intervals between each dose. The results show that an optimal biocoagulant dose of 100 mg/L at 20 minutes produced a turbidity reduction effectiveness of 97.06%. Hardness fell by 12% of its starting value, conductivity and total dissolved solids increased dramatically, and there was a 92.3% reduction in perceived colour, which showed that the use of Moringa seeds as a coagulant had a favourable effect on reducing the concentration of turbidity and colour. Because of this, Moringa (Moringa oleifera Lam.) can be used as a natural source to purify drinking water. The Tukey HSD test applied to the turbidity removal percentages, indicates that the means are not significantly different. However, the experimental evaluation indicates that after 20 minutes, the best results are obtained

¡¡Estequiometria visible!!

Palabras clave: Estequiometría, reactivo límite, reacción química.¡¡Visible stoichiometry¡¡Keywords: Stoichiometry; limit reactive; chemical reaction

Climate change impacts on living marine resources in the Eastern Tropical Pacific

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Identifying the Profile of Helicobacter pylori-Negative Gastric Cancers: A Case-Only Analysis within the Stomach Cancer Pooling (StoP) Project

Background: The prevalence of Helicobacter pylori-negative gastric cancer (HpNGC) can be as low as 1%, when infection is assessed using more sensitive tests or considering the presence of gastric atrophy. HpNGC may share a high-risk profile contributing to the occurrence of cancer in the absence of infection. We estimated the proportion of HpNGC, using different criteria to define infection status, and compared HpNGC and positive cases regarding gastric cancer risk factors. Methods: Cases from 12 studies from the Stomach cancer Pooling (StoP) Project providing data on H. pylori infection status determined by serologic test were included. HpNGC was reclassified as positive (eight studies) when cases presented CagA markers (four studies), gastric atrophy (six studies), or advanced stage at diagnosis (three studies), and were compared with positive cases. A two-stage approach (random-effects models) was used to pool study-specific prevalence and adjusted odds ratios (OR). Results: Among non-cardia cases, the pooled prevalence of HpNGC was 22.4% (n = 166/853) and decreased to 7.0% (n = 55) when considering CagA status; estimates for all criteria were 21.8% (n = 276/1, 325) and 6.6% (n = 97), respectively. HpNGC had a family history of gastric cancer more often [OR = 2.18; 95% confidence interval (CI), 1.03-4.61] and were current smokers (OR = 2.16; 95% CI, 0.52-9.02). Conclusion: This study found a low prevalence of HpNGC, who are more likely to have a family history of gastric cancer in first-degree relatives. Impact: Our results support that H. pylori infection is present in most non-cardia gastric cancers, and suggest that HpNGC may have distinct patterns of exposure to other risk factors.S. Morais, B. Peleteiro, N. Araújo, and N. Lunet received national funding from the Foundation for Science and Technology – FCT (Portuguese Ministry of Science, Technology and Higher Education), under the Unidade de Investigação em Epidemiologia – Instituto de Saúde Pública da Universidade do Porto (EPIUnit; UIDB/04750/2020). S. Morais received funding under the scope of the project “NEON-PC - Neuro-oncological complications of prostate cancer: longitudinal study of cognitive decline” (POCI-01-0145-FEDER-032358; ref. PTDC/SAU-EPI/32358/2017) funded by FEDER through the Operational Program Competitiveness and Internationalization, and national funding from FCT, and the EPIunit – Junior Research – Prog Financing (UIDP/04750/2020). N. Araújo received an individual grant (SFRH/BD/119390/2016) funded by FCT and the ‘Programa Operacional Capital Humano’ (POCH/FSE). C. La Vecchia received funding from the Italian Association for Cancer Research (AIRC, investigator grant no. 21378). All authors received support from the European Cancer Prevention (ECP) Organization for project meetings. All authors thank all MCC-Spain study collaborators (CIBERESP, ISCIII, ISGlobal, ICO, University of Huelva, University of Oviedo, University of Cantabria, University of León, ibs. Granada, Instituto Salud Pública de Navarra, FISABIO, Murcia Regional Health Authority and cols). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact

New FOCUS results on charm mixing and CP violation

We present a summary of recent results on CP violation and mixing in the charm quark sector based on a high statistics sample collected by photoproduction experiment FOCUS (E831 at Fermilab). We have measured the difference in lifetimes for the $D^0$ decays: $D^0 \to K^-\pi^+$ and $D^0 \to K^-K^+$. This translates into a measurement of the $y_{CP}$ mixing parameter in the \d0d0 system, under the assumptions that $K^-K^+$ is an equal mixture of CP odd and CP even eigenstates, and CP violation is negligible in the neutral charm meson system. We verified the latter assumption by searching for a CP violating asymmetry in the Cabibbo suppressed decay modes $D^+ \to K^-K^+\pi^+$, $D^0 \to K^-K^+$ and $D^0 \to \pi^-\pi^+$. We show preliminary results on a measurement of the branching ratio $\Gamma(D^{*+}\to \pi^+ (K^+\pi^-))/\Gamma(D^{*+}\to \pi^+ (K^-\pi^+))$.Comment: 9 pages, 6 figures, requires espcrc2.sty. Presented by S.Bianco at CPConf2000, September 2000, Ferrara (Italy). In this revision, fixed several stylistic flaws, add two significant references, fixed a typo in Tab.