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Ammonia (NH 3 ) volatilization and greenhouse gas (GHG) emission from rice (Oryza sativa L.) fields contaminate the atmospheric environment and lead to global warming. Field trials (2013-2015) were conducted to estimate the influences of different types of fertilization practices on grain yield, NH 3 volatilization, and methane (CH 4 ) and nitrous oxide (N 2 O) emissions in a double rice cropping system in Central China. Results showed that grain yields of rice were improved significantly by using slow/controlled-release urea (S/C-RU). Compared with farmers' fertilizer practice (FFP) treatment, average annual grain yield with application of polymer-coated urea (CRU), nitrapyrin-treated urea (CP), and urea with effective microorganism (EM) treatments was increased by 18.0%, 16.2%, and 15.4%, respectively. However, the effects on NH 3 volatilization and CH 4 and N 2 O emissions differed in diverse S/C-RU. Compared with that of the FFP treatment, the annual NH 3 volatilization, CH 4 emission, and N 2 O emissions of the CRU treatment were decreased by 64.8%, 19.7%, and 35.2%, respectively; the annual CH 4 and N 2 O emissions of the CP treatment were reduced by 33.7% and 40.3%, respectively, while the NH 3 volatilization was increased by 18.5%; the annual NH 3 and N 2 O emissions of the EM treatment were reduced by 6.3% and 28.7%, while the CH 4 emission was improved by 4.3%. Overall, CP showed the best emission reduction with a decrement of 34.3% in global warming potential (GWP) and 44.4% in the greenhouse gas intensity (GHGI), followed by CRU treatment with a decrement of 21.1% in GWP and 31.7% in GHGI, compared with that of the FFP treatment. Hence, it is suggested that polymer-coated urea can be a feasible way of mitigating NH 3 volatilization and CH 4 and N 2 O emission from rice fields while maintaining or increasing the grain yield in Chinese, the double rice cropping system.

Bioequivalence studies of pharmaceutical preparations of medicinal endogenous substances are generally lacking, as the endogenous background is the main obstacle for both experimental design and drug analysis. We conducted a single-dose, self-control, 3-period crossover study to evaluate the bioequivalence of a sustained-release versus an immediate-release preparation of potassium citrate for the treatment of urinary tract stones. This study included a placebo period to monitor the dynamics of endogenous plasma citrate, which could therefore be subtracted during the data processing. Notably, a new convenient method for plasma citrate determination utilizing ultrafiltration extraction and direct reversed-phase high-performance liquid chromatography (HPLC) was successfully applied in the study after validation. To our knowledge, this is the first report using simple reversed-phase HPLC to analyze plasma citrate, and ultrafiltration also significantly simplified the plasma extraction procedure. HPLC was performed using an ODS column, with acetonitrile and 0.02 mol/l sulfuric acid (3:97 v/v) as the mobile phase and ultraviolet detection at 210 nm. Results showed linearity from 10 to 200 microg/ml, an extraction recovery of more than 90% and analysis variability within 15% for additive citrate. The concentration of dog endogenous plasma citrate was determined to be about 30-40 microg/ml. The sustained-release preparation was bioequivalent to the immediate-release preparation in terms of the extent of absorption, but it could not achieve full effects due to a tmax issue., (Copyright 2008 Prous Science, S.A.U. or its licensors. All rights reserved.)

This paper is designed to investigate a novel sustained release system for Traditional Chinese Medicinal Compound Recipe (TCMCR) by incorporating three kinds of pH-dependent gradient-release coated pellets into capsules. In our study, dosage reform was conducted on the TCMCR model drug--Guanxin Suhe Wan (GSW), which is in the traditional form of honey bolus, comprising Styrax, Borneolumsyntheticum, Olbanum, Radix aristolochiae and Lignum santali albi. In this study, the beta-CD inclusion complexes were prepared separately for Styrax, Borneolumsyntheticum and the volatile oil extracted from the mixture of Olbanum, Radix aristolochiae and Lignum santali albi. Pellets were prepared in a centrifugal granulator using the powder layering technique and then divided into 3 equal weight portions and coated with HPMC, HPMCP HP-55 and Eudragit L100/S100 to obtain gradient release in stomach, duodenum and jejunum or ileum respectively. On this basis, a pH-dependent sustained-release pellets system, "Guanxin Suhe Sustained-release Capsules"(GSSC), was prepared by mixing the above three kinds of coated pellets at the weight ratio of 1:1:1. Pharmacokinetic (PK) studies between GSW and GSSC were made on male volunteers and isolated guinea pig hearts by plasma drug concentration method and serum pharmacology method respectively. In plasma drug concentration method, Tmax was 0.42 h and 1.08 h for GSW and GSSC respectively, while in the serum pharmacology method, Tmax was 0.56 h and 0.52 h respectively. The relative bioavailability of GSSC to GSW was 95.62% and 121.82% separately in the above two methods, indicating a similarity between the two methods in predicting the PK behavior of GSSC.