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During weathering and pedogenesis of carbonate rock with poor-Uranium (U) and Thorium (Th), U and Th present the characteristics of strong leaching (especially U) and significant residual enrichment, the cause of which is still unclear. A weathering profile developed by dolomite in karst area of Guizhou province in southwest China was selected, which showed zonation characteristics of bedrock (Y), rock powder (Yf) and soil layer (T1 to T12) from the bottom to up. Through the determination of the occurrence speciation of U and Th in Y and weathering profile, combined with mineralogical, geochemical characteristics and element mass balance calculation, the constraints of U and Th speciation on the geochemical behavior of U and Th during the weathering of carbonate rock were revealed. The results show that U and Th in Y preferentially exist in acid insoluble phase, for example, the contents of U and Th in Y are 0.90 mg·kg-1 and 0.28 mg·kg-1 respectively, while those in acid insoluble matter are 2.34 mg·kg-1 and 2.57 mg·kg-1, respectively, but because the content of acid insoluble matter is extremely low (0.95%), the mass percentage of U and Th in the acid soluble phase in the whole rock is absolutely superior (96% and 86%, respectively). The U and Th in the acid-soluble phase of Y are mainly adsorbed on the crystal surface of carbonate minerals or existed in the cement, and the U and Th in the carbonate lattice only account for a small proportion. During the initial dissolution of Y to form the powdery rock layer (Yt), U and Th released from the surface of carbonate minerals and cements are in an alkaline environment rich in carbonate, and this part of U and Th are leaching out, resulting in strong loss of U and Th in the powdery rock layer ( the loss rates are 83% and 65% respectively). From the Yt to the overlying soil layer T1, the carbonate components are completely dissolved, and the U and Th released from the carbonate lattice show different behaviors which U is completely leached and Th tends to stay in the weathered residue. Thus, in the soil layer T1 formed by the interaction of Y (or Yt) and soil, the residual U is the inheritance of the U in the acid insoluble phase of Y; As for Th, it not only inherits the Th of acid insoluble phase of Y, but also superimposes the Th from carbonate lattice in Y. On the other hand, during the evolution process from Y to Y, and to soil layer T1, with the dissolution of carbonate, the acid insoluble phase also showed a significant tendency of chemical weathering. However, the U and Th in the Y acid insoluble phase are not leached with the decomposition of the acid insoluble phase, but are redistributed among the residual phases. As for the geochemical behavior of U and Th in the evolution of soil profile (T1~T12), it is subject to the occurrence speciation of U and Th in T1 and the change of U and Th occurrence speciation with the upward direction of soil profile. The U and Th released from the carrier minerals are mainly redistributed among the residual solid phases, which weakens the intensity of their further loss.

OBJECTIVE: To study the effect of calorie-enriched formula on postoperative catch-up growth in infants with cyanotic congenital heart disease (CHD). METHODS: A total of 100 infants with cyanotic CHD who underwent surgical operation from January to December, 2017, were randomly divided into a high-calorie group (receiving calorie-enriched formula after surgery) and a conventional group (receiving standard formula after surgery), with 50 infants in each group. All infants were followed up for 6 months. The observation indices included body height, body weight, prealbumin, and N-terminal pro-brain natriuretic peptide before surgery, at the time of ventilator weaning and extubation after surgery, and at 1, 3, and 6 months after surgery. Height-for-age Z-score (HAZ), weight-for-age Z-score (WAZ), and weight-for-height Z-score (WHZ) were also assessed. Adverse reactions were recorded for both groups. RESULTS: There were 25 cases (50%) and 21 cases (42%) of malnutrition in the high-calorie group and the conventional group respectively before surgery (P > 0.05). The nutritional status of the two groups improved 6 months after surgery (P < 0.05). At 6 months after surgery, compared with the conventional group, the high-calorie group had a lower proportion of infants with malnutrition (18% vs 36%, P < 0.05) and also a lower proportation of infants with a WAZ score of < -2 (P < 0.05). The infants with malnutrion in the high-calorie group had higher HAZ, WAZ, and WHZ than those in the conventional group (P < 0.05). No gastrointestinal intolerance was observed in both groups during hospitalization. CONCLUSIONS: Compared with the standard formula, calorie-enriched formula can better help with postoperative catch-up growth in infants with cyanotic CHD.

Drag-reducing polymers (DRPs) are blood-soluble macromolecules that can increase blood flow and reduce vascular resistance. The purpose of the present study is to examine the effects of DRPs on microcirculation in rat hind limb during acute femoral artery occlusion. Two groups of 20 male Wistar rats were subjected to either hemodynamic measurement or contrast enhanced ultrasound (CEU) imaging during peripheral ischemia. Both groups were further subdivided into a DRP-treated group or a saline-treated group. Polyethylene oxide (PEO) was chosen as the test DRP, and rats were injected with either 10 ppm PEO solution or saline through the caudal vein at a constant rate of 5 ml/h for 20 min. Abdominal aortic flow, iliac artery pressure, iliac vein pressure, heart rate, carotid artery pressure and central venous pressure (CVP) were monitored, and vascular resistance was calculated by (iliac artery pressure-iliac vein pressure)/abdominal aortic blood flow. Flow perfusion and capillary volume of skeletal muscle were measured by CEU. During PEO infusion, abdominal aortic blood flow increased (p0.001) and vascular resistance decreased (p0.001) compared to rats that received saline during peripheral ischemia. There was no significant change in ischemic skeletal capillary volume (A) with DRP treatment (p0.05), but red blood cell velocity (β) and capillary blood flow (A×β) increased significantly (p0.05) during PEO infusion. In addition, A, β and A×β all increased (p0.05) in the contralateral hind limb muscle. In contrast, PEO had no significant influence on heart rate, mean carotid artery blood pressure or CVP. Intravenous infusion of drag reducing polymers may offer a novel hydrodynamic approach for improving microcirculation during acute peripheral ischemia.

To investigate the drag-reducing effect of polyethylene oxide (PEO) on the velocity of red blood cells in rat cremaster microcirculation.Blood samples were collected from 6 Wistar male rats (100-110 g) via the post-orbital venous plexus. The red blood cells were separated by centrifugation and labeled by fluorescinisothiocyate (FITC). After successful establishment of cremaster model, the labeled red blood cells were injected into the jugular vein, and the microcirculation was observed and recorded under fluorescence microscope. The hemodynamic parameters and microcirculation video was recorded every 4 min since 4 min before PEO or normal saline injection. Both PEO (10 ppm) and normal saline was injected into the same rat in random sequence at a constant rate of 3.5 ml/h for 20 min followed by observation for another 20 min. The velocity of the labeled-red blood cells was determined by IPP 6.0 software.Compared with normal saline, PEO significantly increased the velocity of the red blood cells in the rat cremaster microcirculation (498.7-/+182.89 microm/s vs 773.54-/+308.27 microm/s, P=0.012). No significant changes in the heart rate and arterial blood pressure were observed during the experiment (P=0.836, P=0.420).PEO at an extremely low concentration can significantly increase the velocity of the red blood cells in rat cremaster microcirculation and produces no significant impact on heart rate and arterial blood pressure.

To investigate the impact of high-dose microbubbles induced by high mechanical index myocardial contrast echocardiography (MCE) on vascular permeability and its recovery time in rats.Thirty male Wistar rats were randomized into 4 MCE groups (groups A-D) and a control group. In the MCE groups, Evans blue was injected at 10 s before MCE (A), immediately after the end of MCE (B), and at 5 min (C) and 20 min after the end of MCE (D). In the control group, the microbubbles and Evans blue were injected at the end of a 5-min ultrasound exposure. All the rats were sacrificed 5 min after Evans blue injection, and the content of Evans blue in the myocardium and the percentage of Evans blue leakage area were determined.The percentage of Evans blue leakage area in groups A, B and C were significantly higher than that in the control group (P0.05), while the percentage was similar between group D and the control group (P0.05). Evans blue contents in groups A and B were significantly higher than that in the control group (P0.05), but groups C and D showed comparable contents with the control group E (P0.05). No significant changes of the heart rates and premature beat number were observed during and after MCE in these groups (P0.05).High mechanical index MCE and a high contrast dose may induce increased microvascular leakage in rats, and the vascular permeability can recover in 20 min after MCE.