The influence of 0.01 mol L-1 NaNO2 addition on the corrosion and passivation of X65 carbon steel in pH 1 to 5 HNO3 solutions was investigated and compared by electrochemical methods and microstructural techniques. In the pH 1 to 5 solutions without NaNO2, the X65 steel presented the electrochemical characteristic of active dissolution, and the corrosion rate of X65 carbon steel decreased gradually with the raise of pH value. By contrast, with the addition of 0.01 mol L-1 NaNO2 in pH 1 to 5 HNO3 solutions, the electrochemical characteristic of X65 carbon steel transferred from the active dissolution in the pH 1 to 5 solutions without NaNO2 to the anodic passivation in the corresponding pH solutions with NaNO2. For the X65 steel in the pH 1 to 5 solutions with NaNO2, with the raise of pH value, the corrosion rate also decreased gradually but the passivation capability strengthened obviously. The corrosion and passivation of X65 carbon steel in pH 1 to 5 HNO3 solutions without and with 0.01 mol L-1 NaNO2 were related to the cathodic reactions of H+ reduction, O2 reduction and NO2-/HNO2 reduction.
Abstract Local administration of toll-like receptor 9 (TLR9), agonist cytidine-phosphate-guanosine oligodeoxynucleotide (CpG ODNs), and CD40 ligand (CD40L) can decrease ligature-induced periodontal inflammation and bone loss in wild type (WT) mouse. Objective: This study aimed to explore whether such effect is dependent on TLR9 signaling. Material and Methods: Purified spleen B cells isolated from WT C57BL/6J mice and TLR9 knockout (KO) mice were cultured for 48 hours under the following conditions: CD40L, CpG+CD40L, CpG at low, medium and high doses. We determined B cell numbers using a hemocytometer at 24 h and 48 h. Percentages of CD1dhiCD5+ B cells were detected by flow cytometry. Interleukin-10 (IL-10) mRNA expression and protein secretion were measured by quantitative real-time polymerase chain reaction (qRT-PCR) and by ELISA, respectively. The silk ligature was tied around the maxillary second molars for 14 days, during which the CpG+CD40L mixture or PBS was injected into palatal gingiva on days 3, 6, and 9. Results: For both WT and TLR9 KO mice, CpG significantly induced B cell proliferation, increased IL-10 mRNA expression and protein secretion of IL-10 but reduced CD1dhiCD5+ B cells population; local injection of CpG+CD40L mixture significantly decreased alveolar bone loss and the number of TRAP-positive cells adjacent to the alveolar bone surface, and significantly increased the gingival mRNA expression of IL-10 and decreased RANKL and IFN-γ mRNA expression. Conclusions: These results indicated that CpG plus CD40L decreased periodontal inflammation and alveolar bone loss in a TLR9-independent manner in ligature-induced experimental periodontitis.
Particle size distribution (PSD) in the soil profile is strongly related to erosion, deposition, and physical and chemical processes. Water cycling and plant growth are also affected by PSD. Material sedimented upstream of the dam constructions formed large areas of deposited farmland (DF) soils on the Chinese Loess Plateau (CLP), which has been the site of the most severe soil erosion in the world. Two DFs without tillage on the CLP were chosen to study the combined effect of erosion and check dams on PSD. Eighty-eight layers (each 10 cm thick) of filled deposited farmland (FDF) soils and 22 layers of silting deposited farmland (SDF) soils of each studied soil profile were collected and 932 soil samples were investigated using laser granulometry. The particle sizes were stratified in both DFs based on soil properties and erosion resistance. The obtained results of clay and silt fractions showed similar horizontal distribution, indicating parallel characteristics of erosion and deposition processes. Fine sand represented the largest fraction, suggesting the preferential detachment of this fraction. The most erodible range of particle sizes was 0.25-0.5 mm, followed by 0.2-0.25 mm in the studied soil profiles. The correlation between particle size and soil water contents tended to increase with increasing water contents in FDF. Due to the abundant shallow groundwater, the relationship between particle size and soil water content in SDF was lost. Further studies on PSD in the DF area are needed to enhance the conservation management of soil and water resources in this region.
A distribuição do tamanho das partículas do solo (PSD) está fortemente relacionada à sua erosão, deposição e aos processos físicos e químicos ocorridos no perfil do solo. A ciclagem da água e o crescimento das plantas também são alterados pelo PSD. Antes da construção das barragens, os solos depositados nas áreas agrícolas (DF) foram amplamente formados no "Loess Plateau", na China (LPC), onde os mais sérios problemas de erosão do solo ocorreram no mundo. Duas DFs, sem preparo do solo, localizadas no LPC foram escolhidas para estudar conjuntamente o efeito da erosão e das barragens na PSD. Novecentas e trinta e duas amostras de solo foram analisadas usando granulometria a laser, a partir de coletas realizadas em 88 camadas (espessura de 10 cm cada camada) formadas por deposição de solos em áreas agrícolas (FDF) e em 22 camadas formadas por deposição de silte (SDF). Os tamanhos das partículas foram estratificados, em ambas as DFs, em função das propriedades do solo e de sua resistência à erosão. Os resultados obtidos para as frações silte e argila mostraram que elas possuem distribuição horizontal similar, indicando características paralelas dos processos de erosão e deposição. A areia fina foi a fração mais encontrada, o que sugere uma separação preferencial desta. Das camadas de solo estudadas, a faixa mais erodível dos tamanhos de partículas foi a de 0,25-0,5 mm, seguida pela de 0,20-0,25 mm. Aumento da correlação entre o tamanho das partículas e o conteúdo de água no solo foi observado na FDF. Devido à abundância de águas subterrâneas superficiais em SDF, os tamanhos de partículas não se relacionaram com o conteúdo de água no solo. Mais estudos sobre a distribuição do tamanho das partículas em DFs são necessários para indicar um melhor manejo e conservação do solo e da água nessas áreas agrícolas.