Macrobicyclic cage amine ligands for copper radiopharmaceuticals: a single bivalent cage amine containing two Lys3-bombesin targeting peptides

The synthesis of new cage amine macrobicyclic ligands with pendent carboxylate functional groups designed for application in copper radiopharmaceuticals is described. Reaction of [Cu((NH(2))(2)sar)](2+) (sar = 3,6,10,13,16,19-hexaazabicyclo[6.6.6]icosane) with either succinic or glutaric anhydride results in selective acylation of the primary amine atoms of [Cu((NH(2))(2)sar)](2+) to give derivatives with either one or two aliphatic carboxylate functional groups separated from the cage amine framework by either a four- or five-atom linker. The Cu(II) serves to protect the secondary amine nitrogen atoms from acylation, and can be removed to give the free ligands. The newly appended carboxylate functional groups can be used as sites of attachment for cancer-targeting peptides such as Lys(3)-bombesin. The synthesis of the first dimeric sarcophagine-peptide conjugate, possessing two Lys(3)-bombesin peptides tethered to a single cage amine, is presented. This species has been radiolabeled with copper-64 at ambient temperature and there is minimal dissociation of Cu(II) from the conjugate even after two days of incubation in human serum.     

Uncovering the complex behavior of hydrogen in Cu2O

The behavior of hydrogen in p-type Cu(2)O has been reported to be quite unusual. Muon experiments have been unable to ascertain the preferential hydrogen site within the Cu(2)O lattice, and indicate that hydrogen causes an electrically active level near the middle of the band gap, whose nature, whether accepting or donating, is not known. In this Letter, we use screened hybrid-density-functional theory to study the nature of hydrogen in Cu(2)O, and identify for the first time the "quasiatomic" site adopted by hydrogen in Cu(2)O. We show that hydrogen will always act as a hole killer in p-type Cu(2)O, and is one likely cause of the low performance of Cu(2)O solar cell devices.     

The role of the graphic calculator in mediating graphing activity

The PIGMI (Portable Information Technologies for supporting Graphical Mathematics Investigations) Project ¹ investigated the role of portable technologies in facilitating development of students' graphing skills and concepts. This paper examines the impact of a recent shift towards calculating and computing tools as increasingly accessible, everyday technologies on the nature of learning in a traditionally difficult curriculum area. The paper focuses on the use of graphic calculators by undergraduates taking an innovative new mathematics course at the Open University. A questionnaire survey of both students and tutors was employed to investigate perceptions of the graphic calculator and the features which facilitate graphing and linking between representations. Key features included visualization of functions, immediate feedback and rapid graph plotting. A follow-up observational case study of a pair of students illustrated how the calculator can shape mathematical activity, serving a catalytic, facilitating and checking role. The features of technology-based activities which can structure and support collaborative problem solving were also examined. In sum, the graphic calculator technology acted as a critical mediator in both the students' collaboration and in their problem solving. The pedagogic implications of using portables are considered, including the tension between using and over-using portables to support mathematical activity.     

High-performance liquid chromatography of nitrophenols with a swept-potential electrochemical detector

The advantages of a swept-potential electrochemical detector are demostrated by application to the high-performance liquid chromatography (h.p.l.c.) of nitrophenols. The primary advantage of the detector is that an additional dimension of information is obtained which can be help identify a chormatographic peak and help to resolve overlapping peaks. The detector retains the selectivity of a differential-pulse detector and yet is general enough to minimize the time for development of new procedures and to detect true methanol-acetate buffer mobile phases. Selectivity factors of the mononitrophenols are independent of the composition of the mobile phase from pH 3.25 to 6.00 and from 40 to 55% methanol. The selectivity factors of dinitrophenols are highly dependent on pH. Limits of detection depend on many parameters but are approximately 1 ng injected for the nitrophenols.     

Purification of synthetic oligodeoxyribonucleotides by ion-exchange high-performance liquid chromatography

Synthetic oligodeoxyribonucleotides ranging from 11 to 37 nucleotides in length and with varying base compositions, prepared by both the phosphotriester and phosphite procedures, have been purified by ion-exchange high-performance liquid chromatography on Whatman Partisil 10/SAX columns using phosphate buffer gradients. The effects of different buffer systems on elution times and resolution have been evaluated. Oligomer composition and length had a marked effect on the resolution achieved. In general the use of formamide buffers gave the best results, particularly in the case of 2'-deoxyguanosine-rich sequences. These methods have also been successfully applied to the purification of mixtures of synthetic oligodeoxynucleotides.     

Self‐Regulation Mechanism for Charged Point Defects in Hybrid Halide Perovskites

Hybrid halide perovskites such as methylammonium lead iodide (CH₃NH₃PbI₃) exhibit unusually low free‐carrier concentrations despite being processed at low‐temperatures from solution. We demonstrate, through quantum mechanical calculations, that an origin of this phenomenon is a prevalence of ionic over electronic disorder in stoichiometric materials. Schottky defect formation provides a mechanism to self‐regulate the concentration of charge carriers through ionic compensation of charged point defects. The equilibrium charged vacancy concentration is predicted to exceed 0.4 % at room temperature. This behavior, which goes against established defect conventions for inorganic semiconductors, has implications for photovoltaic performance.     

ChemInform Abstract: Interplay of Orbital and Relativistic Effects in Bismuth Oxyhalides: BiOF,BiOCl, BiOBr,and BiOI.

Study by using hybrid DFT with explicit treatment of spin—orbit coupling effects and dispersion interactions.     

PHANTOM MAPS AND SPACES OF THE SAME n-TYPE FOR ALL n

1.IntroductionLetXbeaconnectedCWcomplexandX.denoteitsn-skeleton.Amapf:X-YiscalledaphantommapifitsrestrictiontoeachskeletonXuisnullhomotopic.ItiseasytoknowthateveryphantommapfromafiniteCWcomplexortoaspacewithonlyfinitenootrivialhomotopygroupsisnecessarilytrivialuptohomotopy.HenceessentialphantommapcanoccuronlywhenthedomainXisaninfinitedimensionalspaceorthetargetisaspacewithinfinitenontrivialhomotopygroups.Suchmapsappeartobenullhomotopicfromanumberofdifferentpoilltsofview;e.g.,theyinducethe…