نتایج جستجو برای: transition metals

تعداد نتایج: 320706  

Journal: :Science 1998
A Butler

Recent research has revealed that trace metals, particularly transition metals, play important roles in marine productivity. Most of the work has been on iron, which shows a nutrient-depleted profile in the upper ocean. Marine organisms have a variety of means for acquiring iron and other transition metal ions that differ from those of terrestrial organisms.

Journal: :The Journal of chemical physics 2004
J R Kitchin J K Nørskov M A Barteau J G Chen

The modification of the electronic and chemical properties of Pt(111) surfaces by subsurface 3d transition metals was studied using density-functional theory. In each case investigated, the Pt surface d-band was broadened and lowered in energy by interactions with the subsurface 3d metals, resulting in weaker dissociative adsorption energies of hydrogen and oxygen on these surfaces. The magnitu...

Journal: :journal of physical & theoretical chemistry 2004
m. monajjemi1 h. passdar l. saedi r. ghiasi f. mollaamin

more recently medical chemistry research has been focused on proteins that drive and controlcell cycle progression. among them, the cyclin dependent kinases (cdk’s) are a group ofserine/threonine kinases, which rule the transition between successive stages of the cell cycle. theactivity of cdk’s is regulated by multiple mechanisms, including binding to cyclins, which is a broadclass of positive...

2015
Jinsu Kim Kyujoon Lee Toshiro Takabatake Hanchul Kim Miyoung Kim Myung-Hwa Jung

There are many interests to achieve long-range magnetic order in topological insulators of Bi2Se3 or Bi2Te3 by doping magnetic transition metals such as Fe and Mn. The transition metals act as not only magnetic dopants but also electric dopants because they are usually divalent. However, if the doping elements are rare-earth metals such as Gd, which are trivalent, only magnetic moments can be i...

Journal: :Environmental Health Perspectives 2003
Aurelia Walczak-Drzewiecka Janina Wyczólkowska Jaroslaw Dastych

Upon contact with allergen, sensitized mast cells release highly active proinflammatory mediators. Allergen-mediated mast cell activation is an important mechanism in the pathogenesis of atopic asthma. Asthmatic patients are especially susceptible to air pollution. Epidemiologic studies found a positive correlation between severity of symptoms among asthmatic patients and the level of particula...

Journal: :Journal of experimental botany 2003
J L Hall Lorraine E Williams

Transition metals such as Fe, Cu, Mn, and Zn are essential minerals for normal plant growth and development, although they can be toxic when present in excess. Thus, for healthy plant growth, a range of transition metals must be acquired from the soil, distributed around the plant, and their concentrations carefully regulated within different cells and organelles. Membrane transport systems are...

Journal: :The Journal of experimental biology 2007
S W Werneke C Swann L A Farquharson K S Hamilton A M Smith

Several gastropod molluscs produce glues that are interesting because they are dilute gels and yet they produce strong adhesion. Specific glue proteins have been identified that play a central role in this adhesion, possibly by crosslinking other polymers in the gel. This study investigates the role of metals in the action of these glue proteins. Atomic absorption spectrometry showed that glue ...

2014
Xiaozhen Yu Marie-Paule Strub Travis J. Barnard Nicholas Noinaj Grzegorz Piszczek Susan K. Buchanan Justin W. Taraska

Many fluorescent proteins have been created to act as genetically encoded biosensors. With these sensors, changes in fluorescence report on chemical states in living cells. Transition metal ions such as copper, nickel, and zinc are crucial in many physiological and pathophysiological pathways. Here, we engineered a spectral series of optimized transition metal ion-binding fluorescent proteins t...

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