[Effects of fertilization and planting patterns on soil aggregate and carbon distribution in farmland of the Loess Plateau, Northwest China]. / ç§æ¤æ¨¡å¼å’Œæ–½è‚¥å¯¹é»„åœŸæ—±å¡¬å†œç”°åœŸå£¤å›¢èšä½“åŠå ¶ç¢³åˆ†å¸ƒçš„å½±å“.

Based on a long-term experiment in the Changwu Agro-ecological Experimental Station in Xianyang, Shaanxi, China, we examined the effects of fertilization and planting patterns on soil aggregate quantity, aggregate stability and total carbon and organic carbon distribution in different aggregate fractions through dry and wet sieving methods, as well as the TOC combustion method. There were ten treatments, including uncultivated (R), wheat continuous cropping (CK/W), wheat-corn rotation (L), and nitrogen fertilizer (N), phosphorus fertilizer (P), nitrogen and phosphorus fertilizer (NP), organic fertilizer (M), nitrogen and organic fertilizer (NM), phosphorus and organic fertilizer (PM), nitrogen and phosphorus and organic fertilizer (NPM) for CK/W. The results showed that fertilizer application and planting patterns affected soil aggregate distribution and stability, the contents and contribution rates of total C and organic C. Force-stable aggregate was mainly constituted by >0.25 mm aggregate (>67%), which was reduced by fertilization. Continuous cropping decreased micro-aggregate while rotation facilitated it and the effect was larger than fertilization. Water-stable aggregate was mainly comprised of micro-aggregate (<0.25 mm), the contribution of which was larger than 61%. Both fertilizer application and planting pattern reduced water-stable micro-aggregate. Fertilizer application and planting pattern decreased the percentage of aggregate destruction rate (PAD) and increased macro-aggregate (>0.25 mm, R0.25) content. Organic fertilizer significantly improved total C and organic C concentrations in all the fractions of force-stable aggregates. Continuous cropping and rotation cropping increased total C concentration in all the aggregate fractions while rotation cropping significantly decreased organic C concentration. Single N and P fertilization decreased soil total C concentration, while mixed application of N and P fertilizers, and organic fertilizer significantly increased soil total C concentration. The effect of planting patterns on soil total C was lower than that of fertilization. Both continuous cropping and rotation cropping increased soil total C. Mixed application of N and P fertilizers, and organic fertilizer signifi-cantly increased soil organic C concentration while single N and P fertilization decreased it. The effect of planting patterns on soil organic C was lower than that of fertilization, while rotation cropping did not facilitate soil organic C. Micro-aggregate was the most notable size fraction to total carbon and organic C, with the contribution being 21.2%-33.6%. Fertilization and planting pattern increased the contribution rate of micro-aggregate in soil total C. NP and NPM significantly increased the contribution rate of micro-aggregate in soil total C and soil organic C. The effect of rotation cropping was most obvious in driving the contribution rate of micro-aggregate in soil total C and soil organic C.

[Effects of long-term fertilization on soil organic phosphorus fractions and wheat yield in farmland of Loess Plateau]. / 长期施肥对黄土旱塬农田土壤有机磷组分及小麦产量的影响.

Understanding the effects of long-term fertilization on soil organic phosphorus fractions and wheat yield in the Loess Plateau can provide theoretical support for improving phosphorus conversion, utilization, and rational use of fertilizer. We examined the effects of different fertilizer treatments on soil organic phosphorus fractions, wheat yield and soil properties of a farmland in the long-term (1984-2016) positioning test station of Changwu loess soil. There were eight treatments, including no fertilizer (CK), single application of nitrogen fertilizer (N), single application of phosphorus fertilizer (P), application of nitrogen and phosphorus fertilizer (NP), single application of organic fertilizer (M), nitrogen combined with organic fertilizer (MN), phosphorus combined with organic fertilizer (MP), nitrogen and phosphorus combined with organic fertilizer (MNP). The results showed that the range of soil organic phosphorus content was 244.7-429.1 mg·kg-1 after long-term fertilization. Except for the N treatment, organic phosphorus content was significantly increased by 15.4%-47.9% compared to CK. Long-term application of phosphorus fertilizer changed the content of organic phosphorus fractions in the surface soil (0-20 cm). The treatments of MP and MNP significantly increased the contents of labile organic phosphorus and moderately labile organic phosphorus. The treatments of N, P and NP significantly reduced the content of moderately stable organic phosphorus. The treatments of N, P, NP, MN, MP, MNP all significantly increased the highly stable organic phosphorus. The ratio of soil organic phosphorus fractions to total organic phosphorus content was in order of moderately labile organic phosphorus > highly stable organic phosphorus > labile organic phosphorus > moderately stable organic phosphorus. After long-term fertilizer application, the combination of nitrogen and phosphorus fertilizers, especially with organic fertilizers, significantly increased wheat biomass yield and grain yield. Among all the examined soil properties, organic matter, Olsen-P and total inorganic phosphorus were significantly positively correlated with wheat yield. MP and M could significantly increase the content of Olsen-P, total phosphorus, total inorganic phosphorus, labile organic phosphorus and moderately labile organic phosphorus in the loess soil of Loess Plateau. Our results indicated that the organic and phosphorus fertilizers could improve soil phosphorus components that could be more easily absorbed by crops. In summary, the combination of nitrogen and phosphorus fertilizers, especially with organic fertilizers, could increase soil phosphorus supply in the region and promote the wheat yield, which is important for improving soil quality in the Loess Plateau.

[Effects of long-term fertilization on soil microbial abundance in farmland of the Loess Plateau, China]. / 长期施肥对黄土旱塬农田土壤微生物丰度的影响.

Based on a long-term experiment in the Changwu Agro-ecological Experimental Station, the real-time PCR analysis was used to examine the soil microbial abundance and to reveal the effects on soil microbial community under different long-term fertilization systems. The results showed that compared to the CK (barren field), the population of bacteria increased by 21% and archaea by 32% in treatment with inorganic fertilizer application. The abundance of bacteria in the treatment of chemical fertilizer combined with organic fertilizer increased by 37% and archaea by 36%. The treatment with chemical fertilizer mixed with organic fertilizer significantly increased the abundance of bacteria and archaea. The soil AOB increased by 7.13 times while the soil AOA only by 0.2 folds after 30-year application of chemical nitrogen fertilizer. AOB was highly responsive to fertilizer application, especially to nitrogen fertilizer. Compared with the single nitrogen application and the application of nitrogen fertilizer mixed with organic fertilizer, phosphorus fertilizer significantly increased the abundance of nifH and pmoA. The content of nifH, nirS cd and pmoA in the abandoned land was significantly higher than that in the cultivated soil. Results from the correlation analysis on soil basic physical and chemical properties indicated that soil pH, total nitrogen and organic carbon were key factors affecting soil microbial community abundance. In conclusion, long-term fertilization significantly changed soil microbial abundance, and fertilization patterns and cultivating methods had significant effect on microbial community abundance.

CT manifestations of liver involvement in children with Langerhans cell histiocytosis / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To investigate the computed tomography (CT) manifestations of liver involvement in children with Langerhans cell histiocytosis (LCH).</p><p><b>METHODS</b>Retrospective analysis was performed on 9 LCH children with liver involvement confirmed by clinical, laboratory and pathological examinations to investigate the CT manifestations of this condition. These children, including 6 males and 3 females, had undergone both plain CT scan and dual-phase (the arterial and portal venous phases) contrast-enhanced CT scan.</p><p><b>RESULTS</b>The main CT manifestations included hepatomegaly (8 cases); periportal dendritic hypodense lesions or "periportal halo sign" (7 cases) which were mildly or moderately enhanced in the arterial phase; intrahepatic bile duct dilatation (5 cases); lymphadenopathy in the hepatic hilar or retroperitoneal region (4 cases); and diffuse small hypodense nodules (3 cases), which showed annular enhancement on the contrast-enhanced CT scan.</p><p><b>CONCLUSIONS</b>CT findings may be helpful in the early diagnosis and treatment of LCH in children.</p>

Population characteristics and individual variations of enhancement of pancreas and aorta: a contrastive analysis of 2 injection rates / 中南大学学报(医学版)

OBJECTIVE@#To contrastive analyze the population characteristics and individual variations of enhancement modes of normal pancreas and aorta at intravenous injection rates of 3 mL/s and 2 mL/s.@*METHODS@#Sixty-seven patients with normal pancreas were selected, and were divided randomly into 2 groups with different intravenous injection rates (3 mL/s for 35 patients in Group A and 2 mL/s for 32 patients in Group B). Single-level serial dynamic CT scan was performed at the level where the pancreas was best demonstrated. The enhancement values of pancreas and aorta for each time point of each patient were calculated, and the time-density curves of enhancement of pancreas and aorta of each patient were obtained. The peak enhancement and the time to reach the peak enhancement of pancreas and aorta of each individual patient were evaluated, and the 2 groups were compared. The individual variations of the enhancement modes of pancreas and aorta in each group were analyzed.@*RESULTS@#The peak enhancement of pancreas was (75.7+/-17.0) Hu at (43.9+/-6.6) s for Group A, and (66.5+/-16.0) Hu at (55.2+/-5.0) s for Group B; the peak enhancement of aorta was (226.2+/-35.2) Hu at (35.4+/-4.5) s for Group A, (182.8+/-32.8) Hu at (48.0+/-3.7) s for Group B. There were significant differences in both the peak enhancement and the time to reach the peak enhancement of pancreas and aorta between the 2 groups. The coefficients of variation of time to reach the peak enhancement for pancreas and aorta were 15.0% and 12.7% in Group A, and 9.2% and 7.7% in Group B, respectively. The temporal windows of the optimal enhancement of pancreas were (9.7+/-4.5)s and (13.7+/-3.6)s in Group A and B, respectively.@*CONCLUSION@#Better enhancement of pancreas and aorta is obtained at 3 mL/s than 2 mL/s, the time to reach the peak enhancement of pancreas and aorta is comparatively earlier at 3 mL/s than 2 mL/s, and the temporal windows of optimal enhancement of pancreas and aorta are comparatively shorter at 3 mL/s than 2 mL/s.

CT hepatic volume measurement combined with CT perfusion imaging in evaluating the hepatic functional reserve / 中南大学学报(医学版)

OBJECTIVE@#To investigate the application of CT hepatic volume measurement combined with CT perfusion imaging (CTPI) by Spiral CT in evaluating the hepatic functional reserve in cirrhosis.@*METHODS@#CT volume measurement of livers was performed in 32 patients with cirrhosis and 20 patients with normal livers. CTPI had been taken in 25 patients with cirrhosis and 20 patients with normal livers. The hepatic volume, parameter of blood flow perfusion, and liver volume-perfusion index were observed and analyzed. Correlations between graded fractions of hepatic function and liver volume, parameter of perfusion, and liver volume-perfusion index were also analyzed.@*RESULTS@#The values of liver volumes (LV, LVs) reduced gradually (P<0.01) among the groups of hepatic function Grade A, B, and C. The values of the hepatic portal perfusion (HPP), total liver perfusion (TLP), hepatic arterial perfusion index (HAI), and portal perfusion index (PPI) of the cirrhosis group were significantly lower than those of the normal ones (P<0.01). The values of the HPP reduced gradually among Grade A, B, and C (P<0.05 or P<0.01). The values of PPI reduced significantly between Grade C and Grade A, B (P<0.05 or P<0.01). The liver volume-perfusion indexes (VPI, VPIs, VPPI, VPPIs) reduced gradually among Grade A, B, and C (P<0.05 or P<0.01). The correlation between liver volume-perfusion indexes and graded fractions of hepatic function was higher than other indexes, among which the correlation of VPPIs was the highest.@*CONCLUSION@#Changes of volume and blood flow perfusion of the liver are related to the clinical grade of hepatic function. The CT volume measurement combined with CTPI will be a more comprehensive way in evaluating hepatic functional reserve.