Ion Exchange Resin Bags: Factors Affecting Estimates of Nitrogen Availability

1984 ◽  
Vol 48 (5) ◽  
pp. 1181-1184 ◽  
Author(s):  
Dan Binkley
Keyword(s):  
Ion Exchange ◽  
Nitrogen Availability ◽  
Exchange Resin ◽  
Ion Exchange Resin ◽  
Factors Affecting ◽  
Ion Exchange Resin Bags

Nitrogen availability is not affected by frequent fire in a South African savanna

2008 ◽  
Vol 24 (6) ◽  
pp. 647-654 ◽  
Author(s):  
Corli Coetsee ◽  
Edmund C. February ◽  
William J. Bond
Keyword(s):  
Ion Exchange ◽  
South African ◽  
Nitrogen Availability ◽  
Exchange Resin ◽  
Ion Exchange Resin ◽  
African Savanna ◽  
Sampling Points ◽  
Fire Exclusion ◽  
Ion Exchange Resin Bags

Abstract:There is a perception that sustained frequent fires cause nitrogen limitation over the long term (50–100 y) by volatilizing the nitrogen in soil, plant biomass and litter. Here we test this perception in a South African savanna located in the Kruger National Park. At our study site we compare the effects of 50 y of fire exclusion, season (August and February) and frequency (triennial and annual August and triennial February) of burn on nitrogen cycling and availability. We do this using three different methods to determine nitrogen mineralization; in situ incubations, laboratory incubations and ion-exchange resin bags. On each treatment we established two parallel transects 100 m apart with 10 sampling points per treatment along these transects. Daily mineralization rates for in situ incubations were determined monthly from August 2004 to June 2005 at each of the sampling points. Ion-exchange resin bags were buried (5 cm) at the same points and left in the field from August 2004 to August 2005. In February 2005 five randomly located soil samples from each of the four treatments were collected for laboratory incubations using a 7-cm-diameter soil auger. Regardless of method used our results show that there are no significant differences in daily nitrogen mineralization rates after 50 y of different burning treatments from annual burning to fire exclusion. In fact, both in situ and laboratory incubations show that nitrogen availability is higher on the annual burn than the fire exclusion (0.16 μg g−1 soil d−1 vs. 0.11 μg g−1 soil d−1 and 0.46 μg g−1 soil d−1 vs. 0.30 μg g−1 soil d−1 respectively). Perceived negative effects of fire on ecosystem functioning has curbed the use of fire as a management tool with fire often actively suppressed in savanna. The results of our study show that fire can be used more vigorously in mesic African savanna to manipulate tree:grass ratios without negatively affecting the nitrogen cycle.

scholarly journals Study on the Complexation and Release Mechanism of Methylphenidate Hydrochloride Ion Exchange Resin Complex

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4394
Author(s):  
Conghui Li ◽  
Xiaolu Han ◽  
Xiaoxuan Hong ◽  
Xianfu Li ◽  
Hui Zhang ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Exchange Resin ◽  
Drug Loading ◽  
Model Fitting ◽  
Ion Exchange Resin ◽  
Dynamics Simulation ◽  
Taste Masking ◽  
Release Mechanism ◽  
Salt Bridges ◽  
Factors Affecting

Since the advent of ion exchange resin, it has been widely used in many fields, including drug delivery systems. The drug binds to the resin through an exchange reaction to form a drug–resin complex, which can gradually release drugs through the exchange of physiological ions in the gastrointestinal tract, to realize functions such as taste masking and regulating release. In this study, the complexes of methylphenidate hydrochloride and Amberlite IRP69 were prepared and evaluated to explore the mechanism of complexation, influencing factors and release mechanism at a molecular level. Firstly, with the properties of the selected complexes, molecular dynamics simulation was innovatively used to find that the intermolecular interaction between drug molecules and ion exchange resin molecules is mainly caused by the stacking effect of π and salt bridges. Secondly, with the drug loading status as an indicator, the factors affecting the compounding process of the drug and resin were explored. Finally, the release mechanism of the drug–resin complex was studied by mathematical model fitting. In summary, a variety of methods were used to study the mechanism of complexation and release between drug and resin, providing a theoretical basis for promoting the marketing of ion−exchange resin−mediated oral preparations.

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