The bioactivity of 22 essential oils from aromatic and medicinal plants was tested uponAcanthoscelides obtectus Say (Coleoptera, Bruchidae), a pest of kidney bean (Phaseolus vulgaris L.). The insecticidal effect was evaluated by determination of 24- and 48-hr LC50 and LC50 (from 1.50 mg/ dm(3) to more than 1000 mg/dm(3)). Isoprenoids and phenylpropanoids were identified by gas chromatography. The most efficient essential oils were extracted from plants belonging to Labiatae.Origanum marjorana andThymus serpyllum essential oils were the most toxic.

A study of the tensile properties of the leaves of ten indigenous grasses as measured in terms of their breaking force and their breaking tension has shown that grasses differ from one another in these properties. In general the tensile properties of the grasses show little change during the early part of the season, but increase significantly during the autumn and early winter. In general it was noted that the tensile properties of the leaves of those grasses which retained their physical form on attaining maturity tended to be greater than those of the grasses which mature early in the season. UITTREKSEL 'n Studie van die spaneienskappe van die blare van tien inheemse grasse soos gemeet in terme van hulle breekkrag en breekspanning, het aangetoon dat die grasse van mekaar in die eienskappe verskil het en dat daar 'n wisseling, hangend aan die betrokke grasse, met die verloop van tyd plaasgevind het. In die algemeen het die spaneienskappe van die grasblare geen verandering in die voorseisoen aangetoon nie; in die naseisoen egter was daar 'n merkbare verhoging in die eienskappe van die grasblare. In die algemeen is dit opgelet dat die spaneienskappe van die blare wat hulle fisiese vorm met veroudering behou het, hoër was as die wat taamlik vroeg in die seisoen verouder het.

The presence of expansive soils on construction sites is problematic in geotechnical engineering. The swell-shrink behaviour makes these soils not suitable to be used in their natural state. The expansive soil damages cause financial loss yearly more than floods, hurricanes, tornadoes, and earthquakes combined. Moreover, the cost of cut to spoil of expansive soils during construction projects has continued to rise because of the high cost of earthworks, haulage, and the increasing scarcity of spoil areas because of the built environment. Nonetheless, a proper stabilization technique can significantly enhance the expansive soil's properties. The research project attempts to review, report the limits and merits of mechanical and chemical methods utilized to stabilize expansive soils in line with their efficiency, environmental concerns, and cost-effectiveness. A review of mechanical and chemical treatment techniques is conducted in this regard. Ultimately, each stabilization method exhibits its merits and limitations. The lack of standards for the treatment of swelling soils is a significant problem in engineering practice. Specialists in the domain of soil treatment must work together to obtain an optimized stabilization approach and protocol. Moreover, engineers should perform a geoenvironmental assessment appropriate for chemical stabilization methods and additives utilized. This research work contributes as a guideline in the selection and application of chemical and mechanical stabilization methods.

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Purpose -The purpose of the present work is to develop a methodology for making physical models of catchment areas and terrains by rapid prototyping (RP) using geographic information systems (GIS) data. It is also intended to reduce data loss by minimising intermediate data translations. Design/methodology/approach -The GIS data of a catchment area or a terrain were directly translated to an stereo lithography (STL) file. The STL surface was then manipulated in Magics-RP to obtain a solid STL part, which can then be downloaded to a RP machine to obtain a physical model or representation of a terrain or catchtment area. Findings -Intricate geometries of landforms were created with ease and great accuracy in RP machines. Terrain models were created in less time and lower cost than with conventional methods. Research limitations/implications -DEM ASCII XYZ (digital elevation model) data were used to input the required GIS data of specific terrains. Software can be developed for translation and manipulation of DEM, STL and other relevant file formats. This will eliminate any data loss associated with intermediate file transfer. Practical implications -Terrain models were created with ease and great accuracy in RP machines. It takes less time and can be done more costeffectively. Terrain models have intricate geometries and for complex models, it may take months to make using conventional methods. Originality/value -STL surfaces were obtained directly from GIS data for terrain modeling. This work fulfils the need of terrain modeling for catchment management, town-planning, road-transport planning, architecture, military applications, geological education, etc.