Nitric oxide (NO.), a potentially toxic molecule, has been implicated in a wide range of biological functions. Details of its biochemistry, however, remain poorly understood. The broader chemistry of nitrogen monoxide (NO) involves a redox array of species with distinctive properties and reactivities: NO+ (nitrosonium), NO., and NO- (nitroxyl anion). The integration of this chemistry with current perspectives of NO biology illuminates many aspects of NO biochemistry, including the enzymatic mechanism of synthesis, the mode of transport and targeting in biological systems, the means by which its toxicity is mitigated, and the function-regulating interaction with target proteins.

https://science.sciencemag.org/content/sci/258/5090/1898.full.pdf

Biochemistry of nitric oxide and its redox-activated forms

The Environmental Protection Agency (EPA) provides access to information on a variety of topics related to the environment and strives to inform citizens of health risks. The EPA also has an extensive library network that consists of 26 libraries throughout the United States, which provide access to a plethora of information to EPA employees, scientists, and researchers. The EPA implemented a reorganization project to digitize their materials so they would be more accessible to a wider range of users, but this plan was drastically accelerated when the EPA was threatened with a budget cut. It chose to close and reduce the hours and services of some of their libraries. As a result, the agency was accused of denying users the “right to know” by making information unavailable, not providing an adequate strategic plan, and discarding vital materials. This case study explores the background of the digitization project, the practices implemented, and the critiques of the project.

/pdf/the-environmental-protection-agency-3gx4opzrjm.pdf

The Environmental Protection Agency

Atmospheric degradation of volatile organic compounds

(b) Write out the equations for the time dependence of ρ11, ρ22, ρ12 and ρ21 assuming that a light field interaction V = -μ12Ee iωt + c.c. couples only levels |1> and |2>, and that the excited levels exhibit spontaneous decay. (8 marks) (c) Under steady-state conditions, find the ratio of populations in states |2> and |3>. (3 marks) (d) Find the slowly varying amplitude ̃ ρ 12 of the polarization ρ12 = ̃ ρ 12e iωt . (6 marks) (e) In the limiting case that no decay is possible from intermediate level |3>, what is the ground state population ρ11(∞)? (2 marks) 2. (15 marks total) In a 2-level atom system subjected to a strong field, dressed states are created in the form |D1(n)> = sin θ |1,n> + cos θ |2,n-1> |D2(n)> = cos θ |1,n> sin θ |2,n-1>

The Quantum Theory of Light

SIMPSON: a general simulation program for solid-state NMR spectroscopy.

The NMR free induction decay from a spinning sample having inhomogeneous anisotropic interactions (chemical shifts, first order quadrupole couplings) takes the form of a train of rotational spin echoes. The Fourier transform of the echo envelope is a sharp spectrum from which the effects of anisotropy have been removed. The Fourier transform of the echo shape contains information concerning the anisotropies: This information can be extracted by a moment analysis. The effects of localized homonuclear spin–spin interactions are to convert the ’’isotropic’’ spectrum into a characteristic powder pattern. Second order quadrupole coupling produces a similar effect. It is shown in this case that the usual second‐order level shifts cannot be used to calculated this pattern, which must be described by a proper average Hamiltonian theory. Finally it is shown that rotational spin echoes provide a convenient means of studying very slow random molecular rotations (τc≲1 sec).

NMR in rotating solids

Chemical characterization of particulate emissions from diesel engines: A review

Signature size distributions for diesel and gasoline engine exhaust particulate matter

Particle size distributions of light-duty vehicle brake wear debris are reported with careful attention paid to avoid sampling biases. Electrical low-pressure impactor and micro-orifice uniform deposit impactor measurements yield consistent size distributions, and the net particulate matter mass from each method is in good agreement with gravimetric filter measurements. The mass mean diameter of wear debris from braking events representative of urban driving is 6 μm, and the number-weighted mean is 1−2 μm for three currently used classes of lining materials:  low metallic, semimetallic, and non-asbestos organic (NAO). In contrast, the wear rates are very material dependent, both in number and mass of particles, with 3−4 times higher emissions observed from the low metallic linings as compared to the semimetallic and NAO linings. Wind tunnel and test track measurements demonstrate the appearance of micron size particles that correlate with braking events, with approximately 50% of the wear debris being air...

M. Matti Maricq

Papers

NMR in rotating solids

Chemical characterization of particulate emissions from diesel engines: A review

Signature size distributions for diesel and gasoline engine exhaust particulate matter

Airborne brake wear debris: size distributions, composition, and a comparison of dynamometer and vehicle tests.

The effective density and fractal dimension of soot particles from premixed flames and motor vehicle exhaust