Variación de las propiedades físico-mecánicas del adobe estabilizado con dos tipos de polímeros y el uso de barro fermentado, Cajamarca 2022

Esta investigación tuvo como objetivo determinar las propiedades físico-mecánicas del adobe estabilizado, con dos tipos de polímeros (5% Penca y 5% Tuna) y el uso de barro fermentado (10%, 25% y 50%), siguiendo un diseño Experimental aplicado a una muestra de 112 adobes, en cumplimiento a lo establecido por la norma E.080. Por ello los materiales fueron extraídos del Caserío Frutillo Bajo, ya que allí se elabora el ladrillo artesanal. Iniciamos con los estudios de mecánica suelos, tales como: Contenido de humedad, granulometría, límites de consistencia y el ensayo de proctor modificado método A, a continuación se elaboró los adobes compactados en la máquina CINVA RAM, dejándolos secar a temperatura de ambiente, para luego ensayarlos y concluir que los adobes al ser sometidos al ensayo a compresión y flexión superaron el valor mínimo de 10.20 kg/cm² y 0.81 kg/cm² que exige la norma E.080, los adobes ensayados a compresión con 5% de tuna y 5% de penca más la adición a cada muestra del 10%, 25% y 50% de barro fermentado, superaron la resistencia de la muestra patrón en un 109.94% (Tuna) y 95.22% (Penca), siendo la mejor muestra de 5% de tuna más 50% de barro fermentado con un esfuerzo admisible de 21.66 kg/cm². Por el contrario, la resistencia a la absorción de agua fue negativa lo que indica que no se obtuvieron mejoras. Por último, la hipótesis se rechaza debido a que los datos obtenidos difieren con los planteados inicialmente

A qualitative study on resource barriers facing scaled container-based sanitation service chains

Container-based sanitation (CBS) is an increasingly recognised form of off-grid sanitation provision appropriate for impoverished urban environments. To ensure a safely managed and sustainable service, a managing organisation must implement a service chain that performs robustly and cost-effectively, even with an expanding customer base. These ‘CBS operators’ adopt varying approaches to achieve this objective. Following research including interviews with representatives from six current CBS operators, this paper presents a generalised diagrammatic model of a CBS service chain and discusses the three broad thematic challenges currently faced by these organisations. Supplying cover material is a universal problem with hidden challenges when taking advantage of freely available resources. There is no universally applicable approach for the efficient collection of faecal waste despite the high labour costs of waste collection. The best strategy depends on the CBS operator's overall expansion strategy and the location of fixed features within the served community. Although CBS is technically well-suited to being turned into new products within the circular economy, in practice, this requires a diverse range of skills from CBS operators and is hampered by slow growth in other organic waste recovery services and unhelpful regulation. HIGHLIGHTS CBS is a form of off-grid sanitation provision.; Interviews are conducted with representatives from six current CBS operators.; Supplying cover material is a universal problem.; There is no universally applicable approach for the efficient collection of faecal waste.; Although CBS has the p

A qualitative study on resource barriers facing scaled container-based sanitation service chains

Container-based sanitation (CBS) is an increasingly recognised form of off-grid sanitation provision appropriate for impoverished urban environments. To ensure a safely managed and sustainable service, a managing organisation must implement a service chain that performs robustly and cost-effectively, even with an expanding customer base. These ‘CBS operators’ adopt varying approaches to achieve this objective. Following research including interviews with representatives from six current CBS operators, this paper presents a generalised diagrammatic model of a CBS service chain and discusses the three broad thematic challenges currently faced by these organisations. Supplying cover material is a universal problem with hidden challenges when taking advantage of freely available resources. There is no universally applicable approach for the efficient collection of faecal waste despite the high labour costs of waste collection. The best strategy depends on the CBS operator's overall expansion strategy and the location of fixed features within the served community. Although CBS is technically well-suited to being turned into new products within the circular economy, in practice, this requires a diverse range of skills from CBS operators and is hampered by slow growth in other organic waste recovery services and unhelpful regulation

Increased levels of macrophage inflammatory proteins result in resistance to R5-tropic HIV-1 in a subset of elite controllers

Elite controllers (ECs) are a rare group of HIV seropositive individuals who are able to control viral replication without antiretroviral therapy. The mechanisms responsible for this phenotype, however, have not been fully elucidated. In this study, we examined CD4+ T cell resistance to HIV in a cohort of elite controllers and explored transcriptional signatures associated with cellular resistance. We demonstrate that a subgroup of elite controllers possess CD4+ T cells that are specifically resistant to R5-tropic HIV while remaining fully susceptible to X4-tropic and vesicular stomatitis virus G (VSV-G)-pseudotyped viruses. Transcriptome analysis revealed 17 genes that were differentially regulated in resistant elite controllers relative to healthy controls. Notably, the genes encoding macrophage inflammatory protein 1α (MIP-1α), CCL3 and CCL3L1, were found to be upregulated. The MIP-1α, MIP-1β, and RANTES chemokines are natural ligands of CCR5 and are known to interfere with HIV replication. For three elite controllers, we observed increased production of MIP-1α and/or MIP-1β at the protein level. The supernatant from resistant EC cells contained MIP-1α and MIP-1β and was sufficient to confer R5-tropic resistance to susceptible CD4+ T cells. Additionally, this effect was reversed by using inhibitory anti-MIP antibodies. These results suggest that the T cells of these particular elite controllers may be naturally resistant to HIV infection by blocking R5-tropic viral entr

A continental-scale validation of ecosystem service models

Faced with environmental degradation, governments worldwide are developing policies to safeguard ecosystem services (ES). Many ES models exist to support these policies, but they are generally poorly validated, especially at large scales, which undermines their credibility. To address this gap, we describe a study of multiple models of five ES, which we validate at an unprecedented scale against 1675 data points across sub-Saharan Africa. We find that potential ES (biophysical supply of carbon and water) are reasonably well predicted by the existing models. These potential ES models can also be used as inputs to new models for realised ES (use of charcoal, firewood, grazing resources and water), by adding information on human population density. We find that increasing model complexity can improve estimates of both potential and realised ES, suggesting that developing more detailed models of ES will be beneficial. Furthermore, in 85% of cases, human population density alone was as good or a better predictor of realised ES than ES models, suggesting that it is demand, rather than supply that is predominantly determining current patterns of ES use. Our study demonstrates the feasibility of ES model validation, even in data-deficient locations such as sub-Saharan Africa. Our work also shows the clear need for more work on the demand side of ES models, and the importance of model validation in providing a stronger base to support policies which seek to achieve sustainable development in support of human well-being

B Lymphocytes Regulate Dendritic Cell (Dc) Function in Vivo: Increased Interleukin 12 Production by DCs from B Cell–Deficient Mice Results in T Helper Cell Type 1 Deviation

Increasing evidence indicates that dendritic cells (DCs) are the antigen-presenting cells of the primary immune response. However, several reports suggest that B lymphocytes could be required for optimal T cell sensitization. We compared the immune responses of wild-type and B cell-deficient (μMT) mice, induced by antigen emulsified in adjuvant or pulsed on splenic dendritic cells. Our data show that lymph node cells from both control and μMT animals were primed, but each released distinct cytokine profiles. Lymph node T cells from control animals secreted interferon (IFN)-γ, interleukin (IL)-2, and IL-4, whereas those from μMT mice produced IFN-γ and IL-2 but no IL-4. To test whether B cells may influence the T helper cell type 1 (Th1)/Th2 balance by affecting the function of DCs, we immunized mice by transferring antigen-pulsed DCs from wild-type or mutant mice. Injection of control DCs induced the secretion of IL-4, IFN-γ, and IL-2, whereas administration of DCs from μMT animals failed to sensitize cells to produce IL-4. Analysis of IL-12 production revealed that DCs from μMT mice produce higher levels of IL-12p70 than do DCs from wild-type animals. These data suggest that B lymphocytes regulate the capacity of DCs to promote IL-4 secretion, possibly by downregulating their secretion of IL-12, thereby favoring the induction of a nonpolarized immune response