The exchange of water hydroxyl hydrogen bonds between anions and water oxygens is observed directly with ultrafast 2D IR vibrational echo chemical exchange spectroscopy (CES). The OD hydroxyl stretch of dilute HOD in H(2)O in concentrated (5.5 M) aqueous solutions of sodium tetrafluoroborate (NaBF(4)) displays a spectrum with a broad water-like band (hydroxyl bound to water oxygen) and a resolv...

As oxidized RNase is a model for the random conformation state of RNase, the hydrogen exchange kinetics of oxidized RNase approximate the intrinsic conformation-independent chemical exchange rate of the native protein. The energy of activation, the pH(min), and the k(min) of oxidized RNase exchange rates are similar to those reported for amino acid homopolymers. However, unlike the exchange fro...

Background: 66Ga (t1/2=9.49 h, β+: 4.153 MeV, γ: 511, 834, 1039, 2752 keV) has a wide range of applications in different fields of medical sciences. Production of 66Ga became one of our main interests, according to its increasing applications in nuclear medicine, particularly in PET imaging. Materials and Methods: 66 Zn (p,n)66Ga reaction was determined as the best choice for the production of ...

Hydrogen exchange rates have become a valuable probe for studying the relationship between dynamics and structure and for dissecting the mechanism by which proteins fold to their native conformation. Typically measured rates correspond to averages over all protein states from which hydrogen exchange can occur. Here we describe a new NMR experiment based on chemical exchange saturation transfer ...

Determination and recognition of relative distribution of chemical forms of each element and their relationship with physical, chemical and soil clay minerals can help researchers to manage soil fertility better. This research attempted to recognize chemical fractions of zinc (Zn) and copper (Cu) in some surface and subsurface soil samples of Kohgiluyeh and Boyer-Ahmad province and their relati...

Populations of certain unicellular organisms, such as suspensions of yeast in nutrient solutions, undergo transitions to coordinated activity with increasing cell density. The collective behavior is believed to arise through communication by chemical signaling via the extracellular solution. We studied large, heterogeneous populations of discrete chemical oscillators (approximately 100,000) wit...