Outlook on fertilizer use efficiency in the tropics

In this paper efficiency of applied fertilizers under tropical conditions is examined. Understanding of the fertilizer efficiency is particularly important for the developing countries mainly because there is need for enhancement of crop yields at a reduced cost. Many of the soil, plant and climatic factors of the tropical regions that contribute to the efficiency of the applied fertilizers have been discussed. Many of the tropical soils are acidic in nature and in these soils efficiency of applied fertilizer is relatively poor, mainly because plant roots are unable to grow and function to their fullest extent in utilizing the soils available nutrients. To enhance yield potentials there is need for understanding of interaction between crop species and soil and climatic variables. Incorporation and adoptation of a suitable application time can greatly enhance efficiency of urea form of nitrogen. Research findings in tropical soils have shown that an initial broadcast application of P and subsequent band treatment is more effective than either method of application alone. Current crop yields in tropical countries are far below the known yield potentials. Such low production potentials are attributed to the lack of suitable crop germplasms and understanding of improved agronomic practices. Intensification of research activities in fertilizer use efficiency in tropical countries is suggested.Senior author formerly was a Research Advisor to EMBRAPA/IICA/World Bank Program in Brazil.     

Acrylic Resins as Rate-Controlling Membranes in Novel Formulation of a Nine-Day 17β-Estradiol Transdermal Delivery System: In Vitro and Release Modifier Effect Evaluation

The feasibility of transdermal controlled delivery system of 17 β-estradiol was investigated by conducting in vitro release studies. Several new 17 β-estradiol unilaminate adhesive devices capable of releasing 17 β-estradiol in a controlled fashion over a 24-h, 36-h, 96-h, 104-h, 168-h, and 216-h period have been developed using acrylic resins (Eudragits E100, RSPO, and RLPO) as adhesive and rate-controlling polymers. The in vitro release profiles of 17 β-estradiol from various TDS unilaminate devices were characterized in a new developed dissolution tester vessel (total volume 200 ml), using a new paddle. The release of drug from different formulations was measured by a sensitive high-performance liquid chromatographic (HPLC) method. The release of drug from all prepared adhesive devices seems to obey zero-order kinetics (r > 0.98). The effect of two different plasticizers (acetyltributyl citrate [ATBC] and triethyl citrate [TEC]) on the release patterns of 17 β-estradiol from TDS formulations was studied, and they were almost identical. The effect of two different release modifiers, propylene glycol (PG) and myristic acid (MA), on the release pattern of 17 β-estradiol from prepared unilaminate devices was evaluated. It was shown that the use of these release modifiers significantly increased the release of 17 β-estradiol from a TDS unilaminate patch. Furthermore, these data clearly demonstrated that the acrylic resins are suitable polymers for the preparation of 17 β-estradiol TDS adhesive devices.     

Enhancing the Tribological Behavior of Lubricating Oil by Adding TiO2, Graphene,and TiO2/Graphene Nanoparticles

This article investigates the tribological behavior of nanoparticles (NPs) of titanium dioxide anatase TiO₂ (A), graphene, and TiO₂ (A) + graphene added to the pure base oil group ΙΙ (PBO-GΙΙ). The morphology of these two nanostructures of TiO₂ (A) and graphene was characterized by transmission electron microscopy (TEM). Oleic acid (OA) was blended as a surfactant into the formulation to help stabilize the NPs in the lubricant oil. A four-ball test rig was used to determine the tribological performance of six different samples, and an image acquisition system was used to examine and measure the wear scar diameter of the stationary balls. Field emission–scanning electron microscopy (FE-SEM) was used to examine the wear morphology. Energy-dispersive X-ray spectroscopy (EDX), element mapping, and Raman spectroscopy were employed to confirm the presence of (TiO₂ (A) + graphene) and the formation of a tribolayer/film on the mating surfaces. Moreover, a 3D optical surface texture analyzer was utilized to investigate the scar topography and tribological performance. The experiments proved that adding (0.4?wt% TiO₂ (A) + 0.2?wt% graphene) to the PBO-GΙΙ optimized its tribological behavior. These excellent results can be attributed to the dual additive effect and the formation of a tribofilm of NPs during sliding motion. Furthermore, the average reductions in the coefficient of friction (COF), wear scar diameter (WSD), and specific wear rate (SWR) were 38.83, 36.78, and 15.78%, respectively, for (0.4?wt% TiO₂ (A) + 0.2?wt% graphene) nanolubricant compared to plain PBO-GΙΙ lubricant.     

Technical Relevance of Epoxy/Clay Nanocomposite with Organically Modified Montmorillonite: A Review

This review covers almost all known categories of compounds used for nanoclay surface modification with special emphasis on organic modification of layered silicate montmorillonite. Commonly used organic modifiers include quaternary ammonium ions, quaternary phosphonium ions, and amino acids. Dispersion of organomodified nanoclays in epoxy is particularly focused upon in this article. Epoxy-based materials are used as convenient matrices for montmorillonite dispersion since years due to superior properties of resulting polymeric nanocomposites, such as mechanical strength, electrical conductivity, flammability, and thermal stability. Owing to their high performance epoxy nanocomposites have endless applications in aerospace, automotives, construction, electrical, adhesives, and coating industries.     

磷矿擦洗尾矿浮选试验研究

针对云南某地硅钙质擦洗尾矿,采用SJ-01为调整剂,分别在粗选用水玻璃,一次精选用FS作抑制剂,油酸钠和煤油乳化后的复合药剂为捕收剂的浮选工艺流程,获得了精矿P2O5 31．05％、回收率86．08％的浮选指标。     

改良剂对重金属污染根际土壤理化性质影响的研究进展

针对现阶段土壤中重金属污染较为严重的问题及各类修复方法各有利弊的现状,分析了近年来相关学者对于改良剂对重金属污染根际土壤理化性质影响的研究进展,研究了常见有机和无机改良剂对重金属胁迫下根际土壤pH值、氧化还原电位(Eh)、酶活性、化学性质、微生物菌落种群等理化性质的影响以及对重金属的化学沉淀和溶解平衡的影响。后期应加强超富集植物与一般植物根际、非根际理化性质的差异研究;土壤中重金属种类及污染程度与根际土壤理化性质的关系研究;土壤中其他环境因子的影响以及根际土壤中重金属的作用机理方面的研究。     

Ternary Gels of a Polymer Blend and a Recycled Oil: Their Use as Bitumen Modifiers

A blend of random ethylene‐vinyl acetate copolymer (EVA) and triblock styrene‐butadiene‐styrene copolymer (SBS) was dissolved in a recycled engine oil to obtain ternary thermoreversible gels. As the temperature was increased, first a network associated with EVA disappeared, and a second one associated with SBS dominated, maintaining the elastic response of the system. The principal advantage of these ternary systems is that their mechanical properties and thermal stability are better than that of binary gels. These gels, made from waste, can be used as bitumen modifiers to obtain binders of improved properties and good stability, which are useful for road surfacing.

Temperature sweeps of elastic modulus performed at a frequency of 1 Hz.     

改性粉煤灰作橡胶填料的研究

以鸡西发电厂粉煤灰为原料对粉煤灰进行表面改性。从表面改性剂、粉煤灰的粒度、粉煤灰的填加量等几个方面的因素，来探讨改性粉煤灰对橡胶补强性能的影响。实验表明，表面改性后的粉煤灰对橡胶具有较好的补强作用，可替代部分炭黑，可以减少碳黑的用量，降低橡胶的成本，并减少粉煤灰对环境的污染。     

菱镁材料改性研究进展

从菱镁材料成型机理入手,分析了菱镁材料改性外加剂的改性原理及其改性方法,介绍了改性后的菱镁材料具有的各种优异的性能,指明了菱镁材料改性的应用研究方向。