scholarly journals Synthesis of Nanocrystalline Boron Carbide by Direct Microwave Carbothermal Reduction of Boric Acid

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Rodolfo F. K. Gunnewiek ◽  
Pollyane M. Souto ◽  
Ruth H. G. A. Kiminami

The excellent physical and chemical properties of boron carbide make it suitable for many applications. However, its synthesis requires a large amount of energy and is time-consuming. Microwave carbothermal reduction is a fast technique for producing well crystallized equiaxial boron carbide nanoparticles of about 50 nm and very few amounts of elongated nanoparticles were also synthesized. They presented an average length of 82 nm and a high aspect ratio (5.5). The total reaction time was only 20 minutes, which disfavor the growing process, leading to the synthesis of nanoparticles. Microwave-assisted synthesis leaded to producing boron-rich boron carbide. Increasing the forward power increases the boron content and enhances the efficiency of the reaction, resulting in better crystallized boron carbide.

Author(s):  
Zarish Fatima ◽  
Sameer Quazi ◽  
Shreelaxmi Gavas ◽  
Tomasz Karpiński

The advancement in the production and usage of the cerium oxide nanoparticles have diverted the attention of scientists towards their usage in medical field and therapeutic usage. The clinical usage of these Nano ceria is based on their ability to moderate the oxidative stress and this is only because of their ability to change their valent state from +3 to +4 which makes them ideal for scavenging radicals for use in a number of systemic and neurodegenerative disorders. This review aims to synthesize the basic methods used for the synthesis of nanoparticles along with the use of ligand, stabilizing agent and other components. This review also concludes that how various physical and chemical properties of nanoparticles effect the basic biological activities such as antimicrobial activity, cytotoxicity and many others. However, during the standardization, some of the physiochemical properties, methods used for preparation and catalytic abilities must be taken into account.


2007 ◽  
Vol 4 (4) ◽  
pp. 457-460 ◽  
Author(s):  
Subhash Chandra Bajia ◽  
Pawan Swarnkar ◽  
Sudesh Kumar ◽  
Birbal Bajia

An efficient synthesis of phenol-formaldehyde resin has been achieved by using conventional as well as microwave irradiation. Resin samples were tested for their physical and chemical properties. The structures of the resins have been supported by their spectral analysis.


1966 ◽  
Vol 24 ◽  
pp. 101-110
Author(s):  
W. Iwanowska

In connection with the spectrophotometric study of population-type characteristics of various kinds of stars, a statistical analysis of kinematical and distribution parameters of the same stars is performed at the Toruń Observatory. This has a twofold purpose: first, to provide a practical guide in selecting stars for observing programmes, second, to contribute to the understanding of relations existing between the physical and chemical properties of stars and their kinematics and distribution in the Galaxy.


Author(s):  
Mehmet Sarikaya ◽  
Ilhan A. Aksay

Biomimetics involves investigation of structure, function, and methods of synthesis of biological composite materials. The goal is to apply this information to the design and synthesis of materials for engineering applications.Properties of engineering materials are structure sensitive through the whole spectrum of dimensions from nanometer to macro scale. The goal in designing and processing of technological materials, therefore, is to control microstructural evolution at each of these dimensions so as to achieve predictable physical and chemical properties. Control at each successive level of dimension, however, is a major challenge as is the retention of integrity between successive levels. Engineering materials are rarely fabricated to achieve more than a few of the desired properties and the synthesis techniques usually involve high temperature or low pressure conditions that are energy inefficient and environmentally damaging.In contrast to human-made materials, organisms synthesize composites whose intricate structures are more controlled at each scale and hierarchical order.


2017 ◽  
pp. 31-43
Author(s):  
Berta Ratilla ◽  
Loreme Cagande ◽  
Othello Capuno

Organic farming is one of the management strategies that improve productivity of marginal uplands. The study aimed to: (1) evaluate effects of various organic-based fertilizers on the growth and yield of corn; (2) determine the appropriate combination for optimum yield; and (3) assess changes on the soil physical and chemical properties. Experiment was laid out in Randomized Complete Block Design, with 3 replications and 7 treatments, namely; T0=(0-0-0); T1=1t ha-1 Evans + 45-30-30kg N, P2O5, K2O ha-1; T2=t ha-1 Wellgrow + 45-30-30kg N, P2O5, K2O ha-1; T3=15t ha-1 chicken dung; T4=10t ha-1 chicken dung + 45-30-30kg N, P2O5, K2O ha-1; T5=15t ha-1 Vermicast; and T6=10t ha-1 Vermicast + 45-30-30kg N, P2O5, K2O ha-1. Application of organic-based fertilizers with or without inorganic fertilizers promoted growth of corn than the control. But due to high infestation of corn silk beetle(Monolepta bifasciata Horns), its grain yield was greatly affected. In the second cropping, except for Evans, any of these fertilizers applied alone or combined with 45-30-30kg N, P2O5, K2O ha-1 appeared appropriate in increasing corn earyield. Soil physical and chemical properties changed with addition of organic fertilizers. While bulk density decreased irrespective of treatments, pH, total N, available P and exchangeable K generally increased more with chicken dung application.


Author(s):  
O.S. Bezuglova ◽  

Rostov Region belongs to the highly protected natural territories characterized by the continuous plowing. There territories are the only reserves with the soils preserved in their natural state. However, these areas often lack detailed information about the soils quality and composition. Surveying soils on these territories is crucial for determination of their basic physical and chemical properties. The resulted compilation of soil maps could lay a foundation for creating the Red Book of Soils and the formation of a section in the soil-geographical database of the Russian Federation. Subsequently, such information can be used as a background data for the main types of soils in the region. It will be also valuable during monitoring and justification of conservation measures.


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