This paper presents an approach for teaching and learning dc-dc converter design using MathCAD. MathCAD provides advantages that greatly improve teaching and learning process especially when long and complicated design equations are involved such as those found in dc-dc converters. A design example using Excel is presented and then compared with the same example using MathCAD. Experience learne...

Step-up dc-dc converters have to cope with extremely low input voltages when used in combination with energy harvesting sources like thermogenerators, inductive generators or solar cells. The presented dc-dc converter is characterized by a high efficiency, up to 70 % in the input voltage range between 200 mV and 500 mV, and a minimum start-up voltage of 70 mV. It can deliver an output power of ...

Seven pyrrolizidine alkaloids (PAs) have been isolated from Lithospermum canescens and their structures determined by spectroscopical methods. Besides the known lycopsamine, O7-acetyl-lycopsamine and O7-acetylintermedine four new PAs were found. Their structures are O7-(3-hydroxy-3-methyl-butanoyl)-O9-(+)-trachelanthoyl-heliotridine (= O7-(3-hydroxy-3-methyl-butanoyl)-rinderine = canescine), O7...

As plants have been shown to accumulate organic compounds from contaminated sediments, there is a potential for long-lasting ecological impact as a result of contaminant accumulation in riparian areas of wetlands, particularly the accumulation of non-biodegradable contaminants such as perfluorooctanoic acid (PFOA). In this study, commonly found riparian wetland plants including reeds, i.e., Xan...

Two skeletons of the large compsognathid Sinocalliopteryx gigas include intact abdominal contents. Both specimens come from the Jianshangou Beds of the lower Yixian Formation (Neocomian), Liaoning, China. The holotype of S. gigas preserves a partial dromaeosaurid leg in the abdominal cavity, here attributed to Sinornithosaurus. A second, newly-discovered specimen preserves the remains of at lea...

Studies on the lethal effects of plants harmful microorganisms have made them an important and valuable resource for health. Turkey, wherefore junction center three phytogeographic regions, is home to numerous medicinal aromatic with its rich flora. L. canescens a perennial plant that grows in geography extending from Turkey Iran, there are studies only antioxidant capacity essential oil conten...

The development of traditional medicinal plants as raw materials for herbal drugs needs to be standardized. aim the research was standardise ethanol extract Paronema. canescens leaves. determined specific and non-specific parameters. organoleptic has a thick consistency, colour dark brown characteristic non-aromatic odour, slightly bitter taste. soluble content in water 48.1% 80. 3%, respective...