Phenylalanine (Phe) is an amino acid of great interest as coupling of an aromatic group with a chiral hydrophilic region imparts a number of unique properties. Recently there has been an increased interest in the crystalline and gel forms of this compound, part as a result of the complex and undetermined structures of the resulting materials and the relationship of the solid forms of Phe with the disease phenylketonuria. In this report, we highlight the relationship between gelation, crystallization, and the dynamics of self-assembly processes of Phe. We do this by describing the gelation of the amino acid, the gel to crystal relationship, crystal structure predictions for this relatively simple compound, and the dynamics of assembly as determined by NMR in both water and dimethyl sulfoxide. This will provide guidance to future research into Phe assemblies, possible treatments for phenylketonuria, and diseases related to formation of amyloid-like fibers
Phenylalanine is an important amino acid both biologically, essential to human health, and industrially, as a building block of artificial sweeteners. Our interest in this particular amino acid and its derivatives lies with its ability to form gels in a number of solvents. We present here the studies of the influence of halogen addition to the aromatic ring on the gelation properties and we analyse the crystal structures of a number of these materials to elucidate the trends in their behaviour based on the halogen addition to the aromatic group and the interactions that result.
A simple analysis framework is presented to assist transit agencies and station-area communities in making informed planning decisions regarding the highest and best use of parking areas at suburban transit stations. The framework provides the flexibility to tailor values to local settings. The success of high-capacity transit systems depends on well-located and -designed stations. Outside regional commercial business districts, the most favored means of access to transit stations often is a park-and-ride facility. Many suburban station locations have reached full use of limited parking resources, and parking capacity has begun to limit opportunities to increase rail transit ridership. Thus, these major cost transit investments are not fulfilling their full potential as a result of constrained access capacity. Also, many station communities increasingly have been pressuring transit agencies to convert some station patron parking to transit-oriented development (TOD) uses, and some nearby private parking lots have been lost to TOD. Thus, station parking is not only limited but also under pressure for reduction. Little information exists to help transit agencies and local communities understand the highest and best use of limited station site resources. A simple spreadsheet analysis framework is presented to help transit agencies and local communities make informed decisions regarding parking and TOD. This suggested analysis framework focuses on the rail transit ridership implications of parking versus TOD and on the cost of station parking.
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