Comportamento compressivo de um nitossolo: efeito do tamanho de agregados, do teor de água e da pressão aplicada Compression behaviour of a clay soil: effects of aggregate size, water content and applied pressure

A compactação do solo tem sido assunto de intensivas pesquisas nos últimos anos; no entanto, os mecanismos que implicam o processo de compactação dos solos agrícolas, ainda permanecem pouco conhecidos. A contribuição do tamanho de agregados do solo, bem como o efeito do teor de água e da pressão normal aplicada na compactação e pressão de pré-compactação do solo, foi investigada em um Nitossolo Vermelho eutrófico. Amostras de solo deformado, constituídas por agregados menores que 2,5 mm e de 9,3 a 19,4 mm, foram submetidas a ensaio de compressão uniaxial drenado. O índice de vazios e a pressão de pré-compactação foram avaliados. Os resultados obtidos mostram que o tamanho de agregados teve efeito no processo de compactação do solo. A mudança da compactação do solo pode ser prevista em função do estado inicial do solo, da pressão aplicada e do teor de água.<br>Soil compaction has been the subject of intensive researches in the last ten years, but the mechanisms involved in the soil compaction process remain a little known. The contribution of aggregate size of the soil as well as the effect of water content and normal pressure applied on soil compaction and pressure of pre-compaction were investigated in a Clay soil during this trial. Disturbed soil samples constituted by aggregates less than 2.5 mm and 9.3 to 19.4 mm were submitted to a drained compression uniaxial test. The void ratio and the pre-compaction pressure were also evaluated. The results obtained show that the size of the aggregates had effect on the process of soil compaction. The change of soil compaction can be predicted according to the initial state of soil, the applied pressure and the water content of the soil

Doravirine plus lamivudine two-drug regimen as maintenance antiretroviral therapy in people living with HIV: a French observational study

International audienceBackground: Two-drug regimens based on integrase strand transfer inhibitors (INSTIs) and boosted PIs have entered recommended ART. However, INSTIs and boosted PIs may not be suitable for all patients. We aimed to report our experience with doravirine/lamivudine as maintenance therapy in people living with HIV (PLWH) followed in French HIV settings.Methods: This observational study enrolled all adults who initiated doravirine/lamivudine between 1 September 2019 and 31 October 2021, in French HIV centres participating in the Dat'AIDS cohort. The primary outcome was the rate of virological success (plasma HIV-RNA < 50 copies/mL) at Week (W)48. Secondary outcomes included: rate of treatment discontinuation for non-virological reasons, evolution of CD4 count and CD4/CD8 ratio over follow-up.Results: Fifty patients were included, with 34 (68%) men; median age: 58 years (IQR 51-62), ART duration: 20 years (13-23), duration of virological suppression: 14 years (8-19), CD4 count: 784 cells/mm3 (636-889). Prior to switching, all had plasma HIV-RNA < 50 copies/mL. All but three were naive to doravirine, and 36 (72%) came from a three-drug regimen. Median follow-up was 79 weeks (IQR 60-96). Virological success rate at W48 was 98.0% (95% CI 89.4-99.9). One virological failure occurred at W18 (HIV-RNA = 101 copies/mL) in a patient who briefly discontinued doravirine/lamivudine due to intense nightmares; there was no resistance at baseline and no resistance emergence. There were three strategy discontinuations for adverse events (digestive disorders: n = 2; insomnia: n = 1). There was no significant change in CD4/CD8 ratio, while CD4 T cell count significantly increased.Conclusions: These preliminary findings suggest that doravirine/lamivudine regimens can maintain high levels of viral suppression in highly ART-experienced PLWH with long-term viral suppression, and good CD4+ T cell count