Strain Calculations from Hall Measurements in Undoped Al0.25Ga0.75N/GaN HEMT Structures
Abstract
The transport properties of undoped Al0.25Ga0.75N/GaN HEMT structures grown by MOCVD were investigated in a temperature range of 20 K–350 K. With Quantitative Mobility Spectrum Analysis (QMSA) method; it was found that, all conduction in undoped Al0.25Ga0.75N/GaN HEMT structures belong to the two dimensional electron gas (2DEG). With the acception of Hall sheet carrier density is the total polarization induced charge density, strains of 2DEG interfaces were calculated. Calculated strain values are in good agreement with the literature. Effects of the growth parameters of the nucleation layers of samples on the mobility and density of the 2DEG are listed.
S. B. Lisesivdin, A. Yildiz, M. Kasap, and E. Ozbay AIP Conf. Proc. 899 623 (2007).
Savronik, Organize Sanayii Bolgesi, Eskisehir, Turkey
Received: 27 August 2005 Revised: 11 October 2006 Published online: 27 December 2006
Abstract Herein we present a whole new approach that leads to the end results of the general theory of relativity via just the law of conservation of energy (broadened to embody the mass and energy equivalence of the special theory of relativity) and quantum mechanics. We start with the following postulate.
Postulate: The rest mass of an object bound to a celestial body amounts less than its rest mass measured in empty space, and this, as much as its binding energy vis-á-vis the gravitational field of concern.
Many different bacteria and fungi have been able to reduce population density of some kinds of plant parasitic nematodes under laboratory conditions but successes at field scale are rare. Most organisms recognized to be promising for biological control of plant parasitic nematodes are quite spesific in wich nematodes they will attack or have been very diffucult to culture in sufficient quantities to be useful for field application or both. The conditions under which each is most effective are often quite specific and limited. In all, then, commercially effective biological control as a means to reduce the effects of plant parasitic nematodes on laws still appears to be many years away.
Role of Plant Heat Shock Proteins in High Temperature Stress
Mustafa YILDIZ*,Serpil TERZİOĞLU**
ABSTRACT
Higher plants are subjected to a large number of environmental (biotic and abiotic) stresses. Hihg temperature stress lead to a series of morphological, physiological, biochemical and molecular changes that adversely affect plant growth and productivity. Plants synthesize heat-shock proteins (HSPs) in response to high temperature stress. The major HSPs synthesized by eukaryotes, including plants, belong to thoseevolutinoary conserved classes: HSP110,HSP90,HSP70, HSP60, small HSPs and ubiquitin. The synthesis and accumulation of HSPs is accompained by a decrease in normal protein synthesis. The appearence of plamt heat-shock proteins is strongly correlated with the developmend of a condition termed “acquired thermotolerance”. Acquired thermotolerance is induced by sublethal temperatures and leads to enhanced protection of plant cells fromsubseuent heat-induced injury. The acquisition of thermotolerance depends not only upon the synthesis and accumulation of HSPs but also on their cellular localization. During high temperature stress, many enzymes and structural proteins undergo deleterious structural and functional changes. HSPs/molecular chaperones are responsible for many normal cellular processes. In addition, HSPs/molecular chaperons function in the stabilization of proteins and membranes, and in assisting protein refolding under stress conditions.
Keywords: Plants, High temperature stress, Heat shock proteins, Thermal tolerance, Molecular chaperones.
*Afyon Kocatepe Üniversitesi, Fen-Edebiyat Fakültesi, Biyoloji Bölümü, AFYONKARAHİSAR
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**Hacettepe Üniversitesi, Fen Fakültesi, Biyoloji Bölümü, Beytepe-ANKARA
One of the many gifted and renowned Muslim scientists Abu Ali Hasan ibn al-Hasan al-Haytham was bom around 965AD in Basrah. He is sometimes called al-Basri, meaning from the city of Basra in Iraq, and sometinies called al-Misri, meaning that he came from Egypt. in Latin he is known as Alhazen because of the Latinised version of his first name “al-Hasan”. An eminent physician, especially optics, he made his mark as the “father of modem optics.”
