The Kilodegree Extremely Little Telescope (KELT) project is a survey for planetary transits of bright stars. It consists of a small‐aperture, wide‐field automated telescope located at Winer ...Observatory near Sonoita, Arizona. The telescope surveys a set of 26° × 26° fields that together cover about 25% of the northern sky, and targets stars in the range of
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mag, searching for transits by close‐in Jupiters. This paper describes the system hardware and software and discusses the quality of the observations. We show that KELT is able to achieve the necessary photometric precision to detect planetary transits around solar‐type main‐sequence stars.
Tetramethylorthosilicate (tetramethoxysilane; TMOS), a common sol–gel precursor, is found to undergo spontaneous hydrolysis and condensation reactions in a predominantly chloroform/methacrylic acid ...solution, i.e., the major components of a traditional molecular imprinted polymer (MIP) recipe, without the addition of water. The formation of the shorter chain alkoxyoligosilanes is monitored by GC–MS and possible mechanisms for their formation are proposed. While the data collected indicates that the classical sol–gel route may explain the formation of the majority of the silicates, a secondary mechanism may also play a role. The finding that TMOS can undergo sol–gel chemistry in this hydrophobic medium may support a novel synthetic strategy for the preparation of hybrid MIPs (HMIPs): the in situ, serial polymerizations of the inorganic and organic components, respectively. Preliminary evidence to support the potential effectiveness of this strategy is presented.
The synthesis and SAR studies on the N-terminal residue of the ‘address element’ are reported.
A series of benzylic piperazines (e.g.,
4 and
5) attached to an ‘address element’, the dipeptide H-
...d-Tic-
d-
p-Cl-Phe-OH,
3 has been identified as ligands for the melanocortin subtype-4 receptor (MC4R). We describe herein the structure–activity relationship (SAR) studies on the N-terminal residue of the ‘address element’. Several novel dipeptides and reduced dipeptides with high MC4R binding affinities and selectivity emerged from this SAR study.
Homologation and cyclization back to the chiral methine of compound
3 yields achiral 4,4-disubstituted piperidine privileged structures (e.g.,
8a) useful in the construction of melanocortin 4 ...receptor (MC4R) ligands. The piperidine nitrogen was replaced with carbon, oxygen, sulfur, and sulfone with minor erosion of binding. The methyl cyclohexane substituent was the most potent while significant affinity was still seen for smaller lipophilic groups such as ethyl.
Different substituted cyclic aliphatic piperazines provide useful privileged structures for the construction of ligands with affinity for melanocortin 4 receptors.
Aliphatic carbocyclic replacement ...of the benzyl group of compound 1 yielded compounds with high affinity for the melanocortin-4 receptor (MC4R). Compounds with a cyclohexyl group showed a consistent high affinity, while different polar groups with less basicity were good replacements for the original diethyl amines. Substitution of the polar group found in these privileged structures with an aliphatic moiety produced compounds with high affinity for MC4R.
Extensive structure–activity relationship studies utilizing a β-MSH-derived cyclic nonapeptide, Ac-Tyr-Arg-Cys-Glu-His-
d-Phe-Arg-Trp-Cys-NH
2 (
3), led to identification of a series of novel MC-4R ...selective disulfide-constrained hexapeptide analogs including Ac-hCys-His-
d-Phe-Arg-Trp-Cys-NH
2 (
12). The structural modifications associated with profound influence on MC-4R potency and selectivity were ring size, ring conformation, and the aromatic substitution of the
d-Phe7. These cyclic peptide analogs provide novel and enhanced reagents for use in the elucidation of melanocortin-4 receptor-related physiology, and may additionally find application in the treatment of obesity and related metabolic disorders.
Mechanical conditioning represents a potential means to enhance the biochemical and biomechanical properties of tissue‐engineered cell constructs. Bioreactors that can simulate physiologic conditions ...can play an important role in the preparation of tissue‐engineered constructs. Although various forms of bioreactor systems are currently available, these have certain limitations, particularly when these are used for the creation of vascular constructs. The aim of the present report is to describe and validate a novel pressure bioreactor system for the creation of vascular tissue. Here, we present and discuss the design concepts, criteria, as well as the development of a novel pressure bioreactor. The system is compact and easily housed in an incubator to maintain sterility of the construct. Moreover, the proposed bioreactor, in addition to mimicking in vivo pressure conditions, is flexible, allowing different types of constructs to be exposed to various physiologic pressure conditions. The core bioreactor elements can be easily sterilized and have good ergonomic assembly characteristics. This system is a fundamental tool, which may enable us to make further advances in bioreactor technology and tissue engineering. The novel system allows for the application of pressure that may facilitate the growth and development of constructs needed to produce a tissue‐engineered vascular graft.
The melanocortin receptors have been implicated as potential targets for a number of important therapeutic indications, including inflammation, sexual dysfunction, and obesity. We identified compound ...1, an arylpiperazine attached to the dipeptide H-d-Tic-d-p-Cl-Phe-OH, as a novel melanocortin subtype-4 receptor (MC4R) agonist through iterative directed screening of nonpeptidyl G-protein-coupled receptor biased libraries. Structure−activity relationship (SAR) studies demonstrated that substitutions at the ortho position of the aryl ring improved binding and functional potency. For example, the o-isopropyl-substituted compound 29 (K i = 720 nM) possessed 9-fold better binding affinity compared to the unsubstituted aryl ring (K i = 6600 nM). Sulfonamide 39 (K i = 220 nM) fills this space with a polar substituent, resulting in a further 2-fold improvement in binding affinity. The most potent compounds such as the diethylamine 44 (K i = 60 nM) contain a basic group at this position. Basic heterocycles such as the imidazole 50 (K i = 110 nM) were similarly effective. We also demonstrated good oral bioavailability for sulfonamide 39.
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