Compuestos no-estructurales de cementos comerciales y aserrín de maderas argentinas

En el procesamiento mecánico de la madera se generan importantes volúmenes de residuos los cuales en su mayor parte aún no se emplean en la fabricación de componentes para la construcción. En este trabajo investigativo, se evaluó el comportamiento de un compuesto no-estructural de aserrín de dos especies de maderas argentinas combinadas con tres tipos de cementos comerciales. Partículas de maderas (Eucalyptus grandis  y Poplar sp) fueron sometidas a diversos tratamientos y combinadas con tres tipos de cementos comerciales (CPC40, ARI50 y CPP40). Inicialmente, la eficiencia de la reacción fue investigada por medio del ensayo calorimétrico (curva de hidratación). A seguir, probetas cilíndricas fueron sometidas al ensayo de compresión simple, después de 14 días de fabricación. Al mismo tiempo, la velocidad del pulso ultrasónico (VPU) fue evaluada durante la etapa de endurecimiento de las mezclas. Los resultados obtenidos se mostraron muy coherentes entre sí, permitiendo destacar los efectos de los factores naturaleza de la madera, tipo de cemento y tipo de tratamiento, además de las interacciones entre estos factores. La combinación más efectiva fue el empleo de partículas de E. grandis, combinadas indistintamente con los cementos CPC40 o ARI50, adicionados con 3% de cloruro de calcio.The most part of residues generated during wood mechanic processing remains unexplored for construction material non-structural compounds production. Eucalyptus grandis and Cottonwood (Poplar sp) particles were submitted to several treatments, combining three cements (blast furnace slag, high initial strength and puzolanic). Firstly, binder reaction efficacy was investigated by means a calorimetric test (mixture hydration curves). After, cylindrical specimens were submitted to a compression test at 14 days old. Also, ultrasonic pulse velocity (UPV) was obtained during composite hardening process. Results obtained were very coherent detecting the effect of the biomass and cement types, the effect of the treatment applied to the wood particles and the interaction between these parameters. The most effective combination was obtained when a combination of E. grandis particles with blast furnace slag or high initial strength cements, both with 3% calcium chloride addition was used.

Physico-mechanical evaluation of treated bamboo culms

Bamboo is a renewable raw material and is available in tropical and subtropical regions, where it is considered as an inexpensive material. Nevertheless, most bamboo species are highly susceptible to insect and fungi attacks. Basically, bamboo culm protection can be obtained by means of two types of treatment: natural protection and chemical protection. In this study the performance of a Boucherie Modified Method was evaluated, comparing treated bamboo samples (bamboo splits) with untreated samples (control). The effects of the sample position in the culm, chemical solution type and its concentration, treatment duration and the exposition period in two environments (protected and unprotected) were evaluated. Non destructive evaluation - NDE (visual, weight control and ultrasound) and flexure test were applied to the specimens over time. Results obtained showed that dilute solutions, mainly when combined with smaller treatment times, were not effective at protecting bamboo against decay. Results obtained by ultrasound and flexure tests were sensitive enough to detect the best combination of the effect of the evaluated parameters.O bambu é um material renovável e de baixo custo, encontrado em abundância em regiões tropicais e subtropicais; no entanto, a maior parte das espécies de bambu é altamente suscetível ao ataque de fungos e insetos. Basicamente, pode-se aumentar a durabilidade dos colmos de bambu; de duas maneiras: por procedimentos culturais (naturais) e pelo tratamento dos colmos com produtos químicos. Neste trabalho, testou-se a eficiência da aplicação do Método de Boucherie Modificado, comparando-se o aumento na durabilidade das amostras tratadas (taliscas de bambu) com amostras não tratadas ou testemunhas. Para tal, avaliaram-se os efeitos de algumas variáveis, tais como: posição da amostra no colmo, tipos de preservativo e sua concentração, duração do tratamento e tempo de exposição das taliscas em dois ambientes (protegido e exposto) e se realizaram ensaios não destrutivos - END (visual, pesagem das amostras e de ultra-som) e destrutivo (flexão estática). Verificou-se a ineficiência do uso de soluções com baixa concentração, principalmente quando elas foram combinadas com tratamentos de curta duração. Os ensaios de ultra-som e de flexão estática foram suficientemente sensíveis para detectar a melhor combinação do efeito dos parâmetros avaliados.64565

Thermal evaluation of rice husk and cement mortar boards warmed by electric resistance

An alternative proposal for floor heating system by means of electric resistance for both chick and piggy installation is presented in this work. Several formulations of rice husk and cement mortar boards were used. An electronic device controlled all board temperature. This system presented a good efficiency design. The conventional cement mortar mixed with rice husk showed a better performance.Neste trabalho, apresenta-se uma proposta alternativa para o sistema de aquecimento de piso por resistência elétrica em granjas de aves e suínos. Após o dimensionamento do sistema, foram confeccionadas placas com argamassa de cimento, areia e casca de arroz, com diferentes traços, a fim de avaliar esse material alternativo de construção, sendo construído um controlador eletrônico de temperatura para dar mais autonomia ao sistema de aquecimento. O sistema mostrou-se eficiente no controle da temperatura da placa. Dentre os traços analisados, aquele com a placa mista de argamassa convencional e casca de arroz demonstrou melhor desempenho.3745Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Geoeconomic variations in epidemiology, ventilation management, and outcomes in invasively ventilated intensive care unit patients without acute respiratory distress syndrome: a pooled analysis of four observational studies

Background: Geoeconomic variations in epidemiology, the practice of ventilation, and outcome in invasively ventilated intensive care unit (ICU) patients without acute respiratory distress syndrome (ARDS) remain unexplored. In this analysis we aim to address these gaps using individual patient data of four large observational studies. Methods: In this pooled analysis we harmonised individual patient data from the ERICC, LUNG SAFE, PRoVENT, and PRoVENT-iMiC prospective observational studies, which were conducted from June, 2011, to December, 2018, in 534 ICUs in 54 countries. We used the 2016 World Bank classification to define two geoeconomic regions: middle-income countries (MICs) and high-income countries (HICs). ARDS was defined according to the Berlin criteria. Descriptive statistics were used to compare patients in MICs versus HICs. The primary outcome was the use of low tidal volume ventilation (LTVV) for the first 3 days of mechanical ventilation. Secondary outcomes were key ventilation parameters (tidal volume size, positive end-expiratory pressure, fraction of inspired oxygen, peak pressure, plateau pressure, driving pressure, and respiratory rate), patient characteristics, the risk for and actual development of acute respiratory distress syndrome after the first day of ventilation, duration of ventilation, ICU length of stay, and ICU mortality. Findings: Of the 7608 patients included in the original studies, this analysis included 3852 patients without ARDS, of whom 2345 were from MICs and 1507 were from HICs. Patients in MICs were younger, shorter and with a slightly lower body-mass index, more often had diabetes and active cancer, but less often chronic obstructive pulmonary disease and heart failure than patients from HICs. Sequential organ failure assessment scores were similar in MICs and HICs. Use of LTVV in MICs and HICs was comparable (42\ub74% vs 44\ub72%; absolute difference \u20131\ub769 [\u20139\ub758 to 6\ub711] p=0\ub767; data available in 3174 [82%] of 3852 patients). The median applied positive end expiratory pressure was lower in MICs than in HICs (5 [IQR 5\u20138] vs 6 [5\u20138] cm H2O; p=0\ub70011). ICU mortality was higher in MICs than in HICs (30\ub75% vs 19\ub79%; p=0\ub70004; adjusted effect 16\ub741% [95% CI 9\ub752\u201323\ub752]; p<0\ub70001) and was inversely associated with gross domestic product (adjusted odds ratio for a US$10 000 increase per capita 0\ub780 [95% CI 0\ub775\u20130\ub786]; p<0\ub70001). Interpretation: Despite similar disease severity and ventilation management, ICU mortality in patients without ARDS is higher in MICs than in HICs, with a strong association with country-level economic status. Funding: No funding

Identifying associations between diabetes and acute respiratory distress syndrome in patients with acute hypoxemic respiratory failure: an analysis of the LUNG SAFE database

Background: Diabetes mellitus is a common co-existing disease in the critically ill. Diabetes mellitus may reduce the risk of acute respiratory distress syndrome (ARDS), but data from previous studies are conflicting. The objective of this study was to evaluate associations between pre-existing diabetes mellitus and ARDS in critically ill patients with acute hypoxemic respiratory failure (AHRF). Methods: An ancillary analysis of a global, multi-centre prospective observational study (LUNG SAFE) was undertaken. LUNG SAFE evaluated all patients admitted to an intensive care unit (ICU) over a 4-week period, that required mechanical ventilation and met AHRF criteria. Patients who had their AHRF fully explained by cardiac failure were excluded. Important clinical characteristics were included in a stepwise selection approach (forward and backward selection combined with a significance level of 0.05) to identify a set of independent variables associated with having ARDS at any time, developing ARDS (defined as ARDS occurring after day 2 from meeting AHRF criteria) and with hospital mortality. Furthermore, propensity score analysis was undertaken to account for the differences in baseline characteristics between patients with and without diabetes mellitus, and the association between diabetes mellitus and outcomes of interest was assessed on matched samples. Results: Of the 4107 patients with AHRF included in this study, 3022 (73.6%) patients fulfilled ARDS criteria at admission or developed ARDS during their ICU stay. Diabetes mellitus was a pre-existing co-morbidity in 913 patients (22.2% of patients with AHRF). In multivariable analysis, there was no association between diabetes mellitus and having ARDS (OR 0.93 (0.78-1.11); p = 0.39), developing ARDS late (OR 0.79 (0.54-1.15); p = 0.22), or hospital mortality in patients with ARDS (1.15 (0.93-1.42); p = 0.19). In a matched sample of patients, there was no association between diabetes mellitus and outcomes of interest. Conclusions: In a large, global observational study of patients with AHRF, no association was found between diabetes mellitus and having ARDS, developing ARDS, or outcomes from ARDS. Trial registration: NCT02010073. Registered on 12 December 2013