Influencia de la naturaleza del cemento en la compatibilidad con aditivos superplastificantes basados en carboxilatos

An empirical study was conducted to gain a fuller understanding of the interactions taking place in cementsuperplasticiser systems. To this end, two clinkers of known chemical and phase composition were prepared in this study to gain insight into such interactions. One contained no tricalcium aluminate (C1), while the other had a 9% C3A content (C2). These clinkers were ground to approximately 340 m2/kg and blended with gypsum only or gypsum and Klein compound (3CaO·3Al2O3·CaSO4) (1, 2). Sufficient compound was added to C1 to ensure the formation of about the same amount of ettringite after 0.5 and 1 h of hydration as found in cement C2 + gypsum. The admixture used was a carboxylate superplasticiser. Rheology measurements showed that while paste yield stress was correlated to ettringite formation, no such simple relationship was observed for plastic viscosity. Plastic viscosity depended on the total hydrates formed, i.e., not only as ettringite but also as C-S-H gel. The findings revealed that in clinkers with very low sulfate and potassium contents, the rheology of carboxylate-containing cement paste is primarily controlled by ettringite formation.En el presente trabajo se ha realizado un estudio empírico con el objetivo de profundizar en el conocimiento de las interacciones del sistema cemento-superplastificante. Con este fin, se prepararon dos clínkeres con una composición química y de fases conocida: el primero (C1) sin aluminato tricálcico y el segundo (C2) con un contenido en C3A del 9%. Ambos se molieron hasta obtener una superficie específica aproximada de 340 m2/kg y se emplearon con dos adiciones: yeso y el compuesto de Klein (3CaO·3Al2O3·CaSO4) (1, 2). Se añadió la cantidad necesaria del compuesto de Klein a C1 para garantizar la formación, tras 0,5 y 1ª h. de hidratación, de aproximadamente la misma cantidad de etringita en dicho cemento que en la mezcla de cemento C2 y yeso. Se empleó un superplastificante basado en carboxilatos. Los resultados reológicos obtenidos han demostrado que si bien el esfuerzo de cizalla umbral de las pastas muestra una buena correlación con la formación de la etringita, no existe una relación tan clara entre dicho parámetro y la viscosidad plástica. Ésta depende de la cantidad total de hidratos que se generen, es decir, no sólo en forma de etringita sino también como gel C-S-H. A partir de los resultados de los ensayos realizados, se puede afirmar que la formación de etriginta es el factor determinante en la reología de las pastas de cemento preparadas con clínkeres con bajo contenido en sulfato y potasio y aditivadas con un superplastificante basado en carboxilatos

Assessment and comparative analysis of a rapid diagnostic test (Tubex®) for the diagnosis of typhoid fever among hospitalized children in rural Tanzania

Background: Typhoid fever remains a significant health problem in many developing countries. A rapid test with a performance comparable to that of blood culture would be highly useful. A rapid diagnostic test for typhoid fever, Tubex®, is commercially available that uses particle separation to detect immunoglobulin M directed towards Salmonella Typhi O9 lipopolysaccharide in sera.Methods: We assessed the sensitivity and specificity of the Tubex test among Tanzanian children hospitalized with febrile illness using blood culture as gold standard. Evaluation was done considering blood culture confirmed S. Typhi with non-typhi salmonella (NTS) and non - salmonella isolates as controls as well as with non-salmonella isolates only.Results: Of 139 samples tested with Tubex, 33 were positive for S. Typhi in blood culture, 49 were culture-confirmed NTS infections, and 57 were other non-salmonella infections. Thirteen hemolyzed samples were excluded. Using all non - S. Typhi isolates as controls, we showed a sensitivity of 79% and a specificity of 89%. When the analysis was repeated excluding NTS from the pool of controls we showed a sensitivity of 79% and a specificity of 97%. There was no significant difference in the test performance using the two different control groups (p > 0.05).Conclusion: This first evaluation of the Tubex test in an African setting showed a similar performance to those seen in some Asian settings. Comparison with the earlier results of a Widal test using the same samples showed no significant difference (p > 0.05) for any of the performance indicators, irrespective of the applied control group

Nitric Oxide Enhances Desiccation Tolerance of Recalcitrant Antiaris toxicaria Seeds via Protein S-Nitrosylation and Carbonylation

The viability of recalcitrant seeds is lost following stress from either drying or freezing. Reactive oxygen species (ROS) resulting from uncontrolled metabolic activity are likely responsible for seed sensitivity to drying. Nitric oxide (NO) and the ascorbate-glutathione cycle can be used for the detoxification of ROS, but their roles in the seed response to desiccation remain poorly understood. Here, we report that desiccation induces rapid accumulation of H2O2, which blocks recalcitrant Antiaris toxicaria seed germination; however, pretreatment with NO increases the activity of antioxidant ascorbate-glutathione pathway enzymes and metabolites, diminishes H2O2 production and assuages the inhibitory effects of desiccation on seed germination. Desiccation increases the protein carbonylation levels and reduces protein S-nitrosylation of these antioxidant enzymes; these effects can be reversed with NO treatment. Antioxidant protein S-nitrosylation levels can be further increased by the application of S-nitrosoglutathione reductase inhibitors, which further enhances NO-induced seed germination rates after desiccation and reduces desiccation-induced H2O2 accumulation. These findings suggest that NO reinforces recalcitrant seed desiccation tolerance by regulating antioxidant enzyme activities to stabilize H2O2 accumulation at an appropriate concentration. During this process, protein carbonylation and S-nitrosylation patterns are used as a specific molecular switch to control antioxidant enzyme activities

Ascorbic acid and reactive oxygen species are involved in the inhibition of seed germination by abscisic acid in rice seeds

The antagonism between abscisic acid (ABA) and gibberellin (GA) plays a key role in controlling seed germination, but the mechanism of antagonism during this process is not known. The possible links among ABA, reactive oxygen species (ROS), ascorbic acid (ASC), and GA during rice seed germination were investigated. Unlike in non-seed tissues where ROS production is increased by ABA, ABA reduced ROS production in imbibed rice seeds, especially in the embryo region. Such reduced ROS also led to an inhibition of ASC production. GA accumulation was also suppressed by a reduced ROS and ASC level, which was indicated by the inhibited expression of GA biosynthesis genes, amylase genes, and enzyme activity. Application of exogenous ASC can partially rescue seed germination from ABA treatment. Production of ASC, which acts as a substrate in GA biosynthesis, was significantly inhibited by lycorine which thus suppressed the accumulation of GA. Consequently, expression of GA biosynthesis genes was suppressed by the low levels of ROS and ASC in ABA-treated seeds. It can be concluded that ABA regulates seed germination in multiple dimensions. ROS and ASC are involved in its inhibition of GA biosynthesis

European guideline on IgG4-related digestive disease – UEG and SGF evidence-based recommendations

The overall objective of these guidelines is to provide evidence-based recommendations for the diagnosis and management of immunoglobulin G4 (IgG4)-related digestive disease in adults and children. IgG4-related digestive disease can be diagnosed only with a comprehensive work-up that includes histology, organ morphology at imaging, serology, search for other organ involvement, and response to glucocorticoid treatment. Indications for treatment are symptomatic patients with obstructive jaundice, abdominal pain, posterior pancreatic pain, and involvement of extra-pancreatic digestive organs, including IgG4-related cholangitis. Treatment with glucocorticoids should be weight-based and initiated at a dose of 0.6–0.8 mg/kg body weight/day orally (typical starting dose 30-40 mg/day prednisone equivalent) for 1 month to induce remission and then be tapered within two additional months. Response to initial treatment should be assessed at week 2–4 with clinical, biochemical and morphological markers. Maintenance treatment with glucocorticoids should be considered in multi-organ disease or history of relapse. If there is no change in disease activity and burden within 3 months, the diagnosis should be reconsidered. If the disease relapsed during the 3 months of treatment, immunosuppressive drugs should be added

Composition of unfermented, unroasted, roasted cocoa beans and cocoa shells from Peninsular Malaysia

Composition of cocoa beans depends on origin and cocoa processing such as fermentation, drying and roasting. However, less research has been conducted to analyse the composition of Peninsular Malaysia cocoa bean at different processing stages. Thus, the purpose of this study was to determine the proximate, phytosterol level, antioxidant content and activity of Peninsular Malaysia unfermented, unroasted, roasted cocoa beans and cocoa shells. Analysis involved was proximate analysis, total phenolic compound (Folin–Ciocalteu reagent assay), antioxidant activity (2,2-diphenyl-1-picrylhydrazyl scavenging assay) and phytosterol composition. Results show that the crude fiber of unroasted cocoa beans and cocoa shells increased from 17.19 to 28.45% and 13.86 to 16.06% respectively after roasting process. The roasting process is suspected to increase the dietary fiber content of cocoa products due to the interaction between polysaccharides, protein, polyphenolic and Maillard products at high temperature. The total phenolic content in cocoa bean and cocoa shells ranged from 2.42 to 10.82 µg GAE/ml. The unfermented cocoa beans contain significantly (p < 0.05) higher antioxidant activity (92.3%) compared to other samples. This study shows that cholesterol, stigmasterol and β-sitosterol were present in roasted cocoa beans and cocoa shells. Hence, the information on the composition of Malaysia unfermented, unroasted, roasted cocoa beans and cocoa shells are needed to enrich the databases composition as a reference for the cocoa industry

XLIV Konferencja Komitetu Nauk o Żywności i Żywieniu PAN: nauka, technologia i innowacje w żywności i żywieniu

Streszczenia w jęz. angielskimWydarzenie: XLIV Konferencja Komitetu Nauk o Żywności i Żywieniu PAN; Łódź, 3-4 lipca 2019 r.; http://pan.binoz.p.lodz.plOrganizator konferencji: Wydział Biotechnologii i Nauk o Żywności PŁ; Komitet Nauk o Żywności i Żywieniu PAN; Polskie Towarzystwo Technologów ŻywnościProjekt graficzny okładki: Grzelczyk, J.Projekt graficzny okładki: Klewicki, R.Skład: Oracz, J.Za treść zamieszczonych materiałów odpowiadają ich autorzy.Sesje Naukowe Komitetu Nauk o Żywności i Żywieniu Polskiej Akademii Nauk (KNoŻiŻ PAN) są organizowane przez krajowe ośrodki akademickie związane z naukami o żywności i żywieniu w dwuletnich cyklach. Sesje te stanowią największe w skali kraju forum prezentacji najnowszych osiągnięć naukowych i technologicznych w dziedzinie technologii żywności i żywienia człowieka, jak również wymiany poglądów oraz doświadczeń pracowników jednostek naukowych i przedstawicieli przemysłu spożywczego. Tematyka XLIV Sesji dotyczyć będzie szeroko pojętej problematyki związanej z oddziaływaniem żywności i odżywiania na zdrowie człowieka