Search

This study investigates stock recommendations from the three largest finance subreddits on Reddit: wallstreetbets, investing and stocks. A simple strategy that buys recommended stocks weighted by the number of posts per day yields a portfolio with higher average returns at the expense of higher risks than the market for all holding periods, i.e., unfavorable Sharpe ratios. Furthermore, the strategy leads to positive (insignificant) short-term and negative (significant) long-term alphas when considering common risk factors. This is consistent with the idea of “meme stocks”, meaning that the recommended stocks are artificially inflated in the short term when they are recommended, and that the posts contain no information about long-term success. However, it is likely that Reddit users, especially on the subreddit wallstreetbets, have preferences for bets which are not captured by the mean–variance framework. Therefore, we draw on cumulative prospect theory (CPT). We find that the CPT-valuations of the Reddit portfolio exceed those of the market, which may explain the persistent attractiveness for investors to follow social media stock recommendations despite the unfavorable risk-return ratio.

We show the synthesis of an in vivo stable mercury compound with functionality suitable for radiopharmaceuticals. The designed cyclic bisarylmercury was based on the water tolerance of organomercurials, higher bond dissociation energy of Hg−Ph to Hg−S, and the experimental evidence that acyclic structures suffer significant cleavage of one of the Hg−R bonds. The bispidine motif was chosen for its in vivo stability, chemical accessibility, and functionalization properties. Radionuclide production results in 197(m)HgCl2(aq), so the desired mercury compound was formed via a water‐tolerant organotin transmetallation. The Hg‐bispidine compound showed high chemical stability in tests with an excess of sulfur‐containing competitors and high in vivo stability, without any observable protein interaction by human serum assay, and good organ clearance demonstrated by biodistribution and SPECT studies in rats. In particular, no retention in the kidneys was observed, typical of unstable mercury compounds. The natHg analogue allowed full characterization by NMR and HRMS., Stable and versatile: The cyclic bisarylmercury bispidine structure shows exceptional stability against sulfur compounds known to usually react very easily with mercury. Aside from its novelty in mercury chemistry, the in vivo stability paired with the functionalizability of this motif is an important step forward in the development of useful radiomercury pharmaceuticals.

This paper examines whether stock returns are consistent with the value function of prospect theory. We find that beta given a gain yields positive conditional premiums on returns while beta given ...

Ligands combining a bis(phosphonate) group with a macrocycle function as metal isotope carriers for radionuclide-based imaging and for treating bone metastases associated with several cancers. However, bis(phosphonate) pendant arms often slow down complex formation and decrease radiochemical yields. Nevertheless, their negative effect on complexation rates may be mitigated by using a suitable spacer between bis(phosphonate) and the macrocycle. To demonstrate the potential of bis(phosphonate) bearing macrocyclic ligands as a copper radioisotope carrier, we report the synthesis of a new cyclam derivative bearing a phosphinate-bis(phosphonate) pendant (H5te1PBP). The ligand showed a high selectivity to CuII over ZnII and NiII ions, and the bis(phosphonate) group was not coordinated in the CuII complex, strongly interacting with other metal ions in solution. The CuII complex formed quickly, in 1 s, at pH 5 and at a millimolar scale. The complexation rates significantly differed under a ligand or metal ion excess due to the formation of reaction intermediates differing in their metal-to-ligand ratio and protonation state, respectively. The CuII-te1PBP complex also showed a high resistance to acid-assisted hydrolysis (t1/2 2.7 h; 1 M HClO4, 25 °C) and was effectively adsorbed on the hydroxyapatite surface. H5te1PBP radiolabeling with [64Cu]CuCl2 was fast and efficient, with specific activities of approximately 30 GBq 64Cu per 1 μmol of ligand (pH 5.5, room temperature, 30 min). In a pilot experiment, we further demonstrated the excellent suitability of [64Cu]CuII-te1PBP for imaging active bone compartments by dedicated small animal PET/CT in healthy mice and subsequently in a rat femoral defect model, in direct comparison with [18F]fluoride. Moreover, [64Cu]CuII-te1PBP showed a higher uptake in critical bone defect regions. Therefore, our study highlights the potential of [64Cu]CuII-te1PBP as a PET radiotracer for evaluating bone healing in preclinical and clinical settings with a diagnostic value similar to that of [18F]fluoride, albeit with a longer half-life (12.7 h) than 18F (1.8 h), thereby enabling extended observation times.

Objective: The somatostatin receptor subtype 2 (SSTR2) is a suitable target for the diagnosis and therapy of neuroendocrine tumors using radiolabeled ligands [1]. BON-1S cells have been described to express SSTR2 receptors in vitro [2]. We therefore established 2D and 3D cell culture systems of BON-1S cells. For SSTR2 ligand binding, BON-1S cells cultured as monolayer or spheroids were incubated with an SSTR2 agonist (NODAGA-TATE) or an SSTR2 antagonist (NODAGA-JR11). Both were labeled with either 68Ga- or 64Cu and their respective binding and uptake were determined. Understanding the binding data is a prerequisite for using spheroids of BON-1S cells in a Micro Physiological System (MPS) [3]. Methods: Spheroids of SSTR2 containing BON-1S cells were created as follows: Freshly harvested cells were incubated with magnetic nanoparticles in RPMI medium overnight. After magnetic particle uptake, cells were split into a 24-well-plate (1.5 x 10-4 cells/well). In an incubator, the magnetic particles were moved via a magnetic drive for five days, to allow the formation of spheroids [4]. After incubation with the 68Ga- or 64Cu-labeled radioligands (RCY>95%), the BON-1S cells, either as monolayer or as spheroids, were washed and treated with acidic glycine buffer (pH 3.0) to remove the bound but not yet internalized molecules from the outer cellular membrane. After this washing step, the remaining radioligand molecules are assumed to represent internalized molecules [5]. In the monolayer, internalization was determined after 10 minutes, 1 hour and 3 hours after addition of the radioligand to the respective culture. Results: Saturation analysis of radiolabeled NODAGA-TATE as well as NODAGA-JR11 on BON-S1 monolayer yielded similar Kd values in the low nanomolar range (2.3 to 8.6 nM). Affinity of the respective radiolabeled ligand was much lower on BON-1S spheroids, with Kd values around 30 nM for both 64Cu-labeled ligands and almost 60 nM for the 68Ga-labeled ligands. The maximal binding capacity (Bmax) was higher on monolayers and spheroids for radiolabeled JR11 (NODAGA-TATE: monolayer 0.3 pmol/mg, spheroids 0.8 pmol/mg; NODAGA-JR11: monolayer and spheroids 1.2 pmol/mg). The internalization assay showed a ratio of internalized to surface bound radiolabeled NODAGA-TATE of about 80% to 20% for both forms of cell culture, for radiolabeled JR11 a ratio of 8% to 92% was determined, each after a 60 min-incubation time. The internalization after the three time points was ca. 10 times lower in case of radiolabeled JR11 (0.25% (TATE) versus maximal 0.03% (JR11) of administered activity amount/µg protein). Conclusions: Using monolayer or spheroids of BON-1S cells (the latter were generated by the iron nanoparticle method) we could estimate reliable and reproducible binding parameters for a radiolabeled agonist and antagonist of SSTR2. There are obvious differences in binding affinities of the examined radiolabeled conjugates in monolayer cell culture compared to the spheroids. Acknowledgements: The SSTR2 expressing BON-1S cells were kindly given by Prof. Dr. Wiedenmann, University Hospital Charité Berlin. References: [1] Eychenne, Molecules 2020, 25, 4012. [2] Exner, Front Endocrinol 2018, 9, 146. [3] Busek, J Sens Sens Syst 2016, 5, 228. [4] Noel, J Vis Exp 2017, 126, e56081. [5] Matzku, Cancer Res 1986, 46, 3848.

This paper describes a model in which a network of interbank loans leads to a severe amplification of the previously unanticipated insolvency of one bank. Banks that cannot rule out an indirect hit react by selling assets and hoarding liquidity. While this potentially lowers illiquidity risks, it depresses market liquidity and prices. This leads to a negative externality by which sales to acquire liquidity simultaneously lead to lower global sale proceeds and thus to a greater number of insolvencies inducing deadweight losses. Thus, the distribution of information on the network has a direct impact on welfare by itself. Der Zusammenhang zwischen unvollständigen Informationen über das Banknetzwerk und Adressenausfallrisiken Zusammenfassung In dieser Arbeit wird ein Modell betrachtet, in dem das Netzwerk aus Interbankenkrediten die Folgen der unerwarteten Insolvenz einer einzelnen Bank drastisch verstärkt. Banken, die indirekte Verluste nicht ausschließen können, reagieren mit dem Verkauf von Vermögenswerten und dem Horten von Liquidität. Dies führt zwar potenziell zu ­einer Senkung der Illiquiditätsrisiken, drückt aber die Marktliquidität und Preise. Es kommt zu einem negativen externen Effekt, da die Verkäufe zur Liquiditätsbeschaffung gleichzeitig zu geringeren Verkaufserlösen und damit zu einer größeren Anzahl von Insolvenzen, die Wohlfahrtsverluste mit sich bringen, führen. Demnach hat die Informa­tionsverteilung im Bankennetzwerk einen direkten Einfluss auf die Wohlfahrt. JEL Classification: G01, G11, G21, G33

This study examines drivers of investment probability in equity-based crowdfunding using a hand-collected and comprehensive data set from a well-established platform. The analysis confirms several effects that have been reported in the recent literature on other crowdfunding markets. Extending recent research, we study moderators of local preferences of investors. Novel to the literature, we find that (1) local preferences are more pronounced in campaigns of younger ventures, (2) herding-like behaviour is stronger in local campaigns and (3) local investors are more responsive to updates posted by entrepreneurs, compared to non-locals. Our results suggest that investors allocate more attention to campaigns for which they have information advantages, such as local campaigns, due to their limited capacity to process information. Such behaviour may eventually amplify information asymmetry and local preferences. Our findings have practical implications for entrepreneurs, investors and platforms.

In metal chalcogenide nanocrystals (NCs), the cations can be partially or fully replaced with other cations through the so-called cation exchange (CE) reactions. Here, we took advantage of these CE reactions to replace the cations on different chalcogenides NCs with 64Cu ions in order to radiolabel them. With respect to other approaches reported in the literature, our CE protocol is easily transferable to the clinic. It requires indeed one single step, in which the water-soluble NCs are mixed with a 64Cu copper(II) chloride solution of high specific activity, in the presence of vitamin C used as a reducing agent for Cu(II) to Cu(I)). Given the quantitative replacement of the cations of the NCs with 64Cu(I), a high radiochemical yield up to 90-95% can be reached. Provided that there is no free 64Cu, no purification step is needed, making the protocol straightforward. At the same time, the amount of NCs required for the exchange is so low (in the range of μg) that the dose of NCs shows no intrinsic cytotoxicity. This protocol works on different types of metal chalcogenide NCs. In ZnSe and ZnS NCs, the Zn(II) ions are exchanged with 64Cu (I) ions, and in CuFeS2 NCs the Fe(III) ions are exchanged with 64Cu(I). To ensure the stability of the NCs during and after the CE reaction, a multi-anchoring coating procedure based on PEG, cysteamine and poly-maleic anhydride was proven to be more efficient than the use of monothiol PEG ligands. With our approach we managed to achieve an unprecedented high specific activity, i.e. the amount of 64Cu radionuclide loaded per NC dose, to dispatch remarkable ionizing effects. Indeed, by exploiting a volumetric cations exchange, our strategy enables to concentrate a large dose of 64Cu (18.5 MBq) in a small NC dose (0.4 μg), reaching a specific activity of about 50 TBq/g. Remarkably, for CuFeS2 NCs even after the CE, the radiolabeled 64Cu:CuFeS2 NCs still show the characteristic dielectric resonance that enables the generation of heat under laser exposure for clinical use (1 W/cm2). The synergic toxicity of photo-ablation and 64Cu radiation exposure is here demonstrated in an in vitro study on glioblastoma and epidermoid carcinoma tumor cells.

This study examines interdependencies between investments of equity crowdfunders. Based on hand-collected data from a well-established equity-crowdfunding platform, we find strong indication that investors observe previous investments to determine their willingness to pay for equity shares. Furthermore, the investment behavior of predecessors may lead investors to deviate from average investment behavior. In particular, investors are willing to pay more than the average investment, when the focal campaign is hot or there have been many large investments in the campaign. Remarkably, a high number of all previous investments over the entire period of the campaign as well as co-financing by presumably sophisticated investors negatively influence willingness to pay. This suggests that crowd investors are subject to partial crowding-out. These findings are different on the platform level, which suggests that investors’ behavior is rather information than sentiment-driven.

The epidermal growth factor receptor (EGFR) represents an important molecular target for both radiotracer-based diagnostic imaging and radionuclide therapy of various cancer entities. For the delivery of radionuclides to the tumor, peptides hold great potential as a transport vehicle. With respect to EGFR, the peptide YHWYGYTPQNVI (GE11) has been reported to bind the receptor with high specificity and affinity. In the present study, GE11 with β-alanine (β-Ala-GE11) was conjugated to the chelating agent p-SCN-Bn-NOTA and radiolabeled with 64Cu for the first radio pharmacological evaluation as a potential probe for positron emission tomography (PET)-based cancer imaging. For better water solubility, an ethylene glycol-based linker was introduced between the peptide’s N terminus and the radionuclide chelator. The stability of the 64Cu-labeled peptide conjugate and its binding to EGFR-expressing tumor cells was investigated in vitro and in vivo, and then compared with the 64Cu-labeled EGFR-targeting antibody conjugate NOTA-cetuximab. The GE11 peptide conjugate [64Cu]Cu-NOTA-linker-β-Ala-GE11 ([64Cu]Cu-1) was stable in a buffer solution for at least 24 h but only 50% of the original compound was detected after 24 h of incubation in human serum. Stability could be improved by amidation of the peptide’s C terminus (β-Ala-GE11-NH2 (2)). Binding assays with both conjugates, [64Cu]Cu-1 and [64Cu]Cu-2, using the EGFR-expressing tumor cell lines A431 and FaDu showed no specific binding. A pilot small animal PET investigation in FaDu tumor-bearing mice revealed only low tumor uptake (standard uptake value (SUV)

Recent research suggests that competition is reduced by common ownership. Based on this idea, we build a model in which strategic investors have an incentive to reduce the correlation between companies they have invested in. Therefore, we hypothesize that pairwise correlations between stock returns decrease with increasing common strategic ownership. To test this hypothesis empirically, we construct a measure that captures the presence of strategic investors in both companies. Using NYSE data and several control variables, we find a negative relation between this measure and pairwise correlations. This result provides support for the anticompetitive effects of common ownership.

Unnatural mirror image l-configured oligonucleotides (L-ONs) are a convenient substance class for the application as complementary in vivo recognition system between a tumor specific antibody and a smaller radiolabeled effector molecule in pretargeting approaches. The high hybridization velocity and defined melting conditions are excellent preconditions of the L-ON based methodology. Their high metabolic stability and negligible unspecific binding to endogenous targets are superior characteristics in comparison to their d-configured analogs. In this study, a radiopharmacological evaluation of a new l-ONs based pretargeting system using the epidermal growth factor receptor (EGFR) specific antibody cetuximab (C225) as target-seeking component is presented. An optimized PEGylated 17mer-L-DNA was conjugated with p-SCN-Bn-NOTA (NOTA′) to permit radiolabeling with the radionuclide 64Cu. C225 was modified with the complementary 17mer-L-DNA (c-L-DNA) strand as well as with NOTA′ for radiolabeling and use for posi...

Radiolabeled α-melanocyte-stimulating hormone (α-MSH) derivatives have a high potential for diagnosis and treatment of melanoma, because of high specificity and binding affinity to the melanocortin-1 receptor (MC1R). Hence, the α-MSH-derived peptide NAP-NS1 with a β-Ala linker (ε-Ahx-β-Ala-Nle-Asp-His-D-Phe-Arg-Trp-Gly-NH

Regardless of its high positron energy

Regardless of its high positron energy, 68 Ga-labeled PSMA ligands have become standard of care in metabolic prostate cancer imaging. 64 Cu, a radionuclide with a much longer half-life (12.7 h), is available for PSMA labeling allowing imaging much later than 68 Ga. In this study, the diagnostic performance of 64 Cu-labeled PSMA was compared between early and late scans. Sixteen men (median age: 70 y) with prostate cancer in different stages underwent 64 Cu-PSMA-617-PET/CT 2 and 22 hours post tracer injection. Pathologic and physiologic uptakes were analyzed for both points of time. Pathologic tracer accumulations occurred in 12 patients. Five patients presented with pathologic uptake in 17 different lymph nodes, two patients showed pathologic bone uptake in nine lesions, and seven patients had pathologic PSMA uptake in eight prostatic lesions. Physiologic uptake of the renal parenchyma, urine bladder, and salivary glands decreased over time, while the physiologic uptake of liver and bowel increased. In the present study, 64 Cu-PSMA-617-PET demonstrated to be feasible for imaging prostate cancer for both the primary tumor site and metastases. Later imaging showed no additional, clinically relevant benefit compared with the early scans. At least the investigated time points we chose did not vindicate the additional expenditure.

Radiolabeled alpha-melanocyte-stimulating hormone (alpha-MSH) derivatives have a high potential for diagnosis and treatment of melanoma, because of high specificity and binding affinity to the melanocortin-1 receptor (MC1R). Hence, the alpha-MSH-derived peptide NAP-NS1 with a beta-Ala linker (epsilon-Ahx-beta-Ala-Nle-Asp-His-D-Phe-Arg-Trp-Gly-NH2) was conjugated to different chelators: either to NOTA (p-SCN-Bn-1,4,7-triazacyclononane-1,4,7-triacetic acid), to a hexadentate bispidine carbonate derivative (dimethyl-9-(((4-nitrophenoxy)carbonyl)oxy)-2,4-di(pyridin-2-yl)-3,7-bis(pyridin-2-ylmethyl)-3,7-diazabicyclo[3.3.1]nonane-1,5-dicarboxylate), or to DMPTACN (p-SCN-Ph-bis(2-pyridyl-methyl)-1,4,7-triaza-cyclononane), labeled with Cu-64, and investigated in terms of radiochemical and radiopharmacological properties. For the three Cu-64-labeled conjugates negligible transchelation, suitable buffer and serum stability, as well as appropriate water solubility, was determined. The three conjugates exhibited high binding affinity (low nanomolar range) in murine B16F10, human MeWo, and human TXM13 cells. The B-max values of [Cu-64]Cu-bispidine-NAP-NS1 ([Cu-64]Cu-2) and [Cu-64]Cu-DMPTACN-NAP-NS1 ([Cu-64]Cu-3) were higher than those of [Cu-64]Cu-NOTA-NAP-NS1 ([Cu-64]Cu-1), implying that different charged chelate units might have an impact on binding capacity. Preliminary in vivo biodistribution studies suggested the main excretion pathway of [Cu-64]Cu-1 and [Cu-64]Cu-3 to be renal, while that of [Cu-64]Cu-2 seemed to be both renal and hepatobiliary. An initial moderate uptake in the kidney decreased clearly after 60 minutes. All three Cu-64-labeled conjugates should be considered for further in vivo investigations using a suitable xenograft mouse model.

Through the choice of appropriate layer thicknesses, the bandgap of InAs/Ga(As)Sb type II superlattices (T2SLs) can be engineered in a wide range covering the mid-wavelength and long-wavelength infrared (MWIR, 3 μm - 5 μm and LWIR, 8 μm - 12 μm) spectral regions. Using this material system, Fraunhofer IAF develops bi-spectral MWIR image sensors based on homojunction photodiodes for missile warning applications and pursues modern heterojunction approaches as well as heteroepitaxial growth of T2SLs on GaAs. We discuss topics arising from efforts to improve the manufacturability of our bi-spectral arrays and report on the progress of the integration with MWIR heterojunction designs that exhibit reduced dark currents.

The epidermal growth factor receptor (EGFR) represents an important molecular target for both radiotracer-based diagnostic imaging and radionuclide therapy of various cancer entities. For the delivery of radionuclides to the tumor, peptides hold great potential as a transport vehicle. With respect to EGFR, the peptide YHWYGYTPQNVI (GE11) has been reported to bind the receptor with high specificity and affinity. In the present study, GE11 with β-alanine (β-Ala-GE11) was conjugated to the chelating agent p-SCN-Bn-NOTA and radiolabeled with

Price-taking behavior seems to contradict rationality if a price effect is to be expected. This paper identifies a strategic effect between price-takers and non-price-takers on financial markets. It results from the liquidity reduction non-price-taking induces. Thus, a trade-off between the benefits of calculating price impacts correctly and market liquidity exists. It is shown that price-takers may benefit more from trading than their fully rational counterparts do. Moreover, it is demonstrated that when the choice of behavior is unobservable and decision costs exist an investor would profit more as a non-price-taker when his trading potential is large, and more as a price-taker when it is small. However, when the choice of behavior is observable it is the other way around. If various rounds of trading take place, an investor’s terminal endowment converges to his risk tolerance share. Thus, an efficient allocation is obtained. Furthermore, a paradox concerning the endogenous choice of manners of calculation is identified.

In this study, approaches were developed to examine the phenotypes of nonviable clinical varicella-zoster virus (VZV) strains with amino acid substitutions in the thymidine kinase (TK) (open reading frame 36 [ORF36]) and/or DNA polymerase (Pol) (ORF28) suspected to cause resistance to antivirals. Initially, recombinant TK proteins containing amino acid substitutions described as known or suspected causes of antiviral resistance were analyzed by measuring the TK activity by applying a modified commercial enzyme immunoassay. To examine the effects of these TK and Pol substitutions on the replication of recombinant virus strains, the method of en passant mutagenesis was used. Targeted mutations within ORF36 and/or ORF28 and an autonomously expressed gene of the monomeric red fluorescent protein for plaque identification were introduced into the European wild-type VZV strain HJO. Plaque reduction assays revealed that the amino acid substitutions with unknown functions in TK, Q303stop, N334stop, A163stop, and the deletion of amino acids 7 to 74 aa (Δaa 7 to 74), were associated with resistance against acyclovir (ACV), penciclovir, or brivudine, whereas the L73I substitution and the Pol substitutions T237K and A955T revealed sensitive viral phenotypes. The results were confirmed by quantitative PCR by measuring the viral load under increasing ACV concentrations. In conclusion, analyzing the enzymatic activities of recombinant TK proteins represent a useful tool for evaluating the significance of amino acid substitutions in the antiviral resistance of clinical VZV strains. However, direct testing of replication-competent viruses by the introduction of nonsynonymous mutations in a VZV bacterial artificial chromosome using en passant mutagenesis led to reliable phenotypic characterization results.

Two-photon quantum well infrared photodetectors (QWIPs) are nonlinear detectors for the mid-infrared and terahertz regimes optimized for resonant two-photon absorption. Here we present first results on two-photon QWIP samples based on the GaAs/AlGaAs material system with intersubband energies between 25 and 12 meV (6–3 THz) confirmed by photocurrent spectra. The dark current showed large discontinuities, presumably caused by impact ionization. We performed interferometric autocorrelation experiments at the free-electron laser FELBE and observed nonlinear interferograms for all samples.

We show coherent wireless transmission at carrier frequencies within 0.30+0.02 THz using up to 20 QPSK-modulated subcarriers with a symbol rate of 0.75 GBd each, leading to an aggregate line rate of 30 Gbit/s. We exploit optoelectronic techniques, both for THz generation and coherent reception.

Improved aluminum-gallium-nitride (Al x Ga 1-x N) p-i-n photodetectors with different active regions are reported, designed for the measurement of UV-A (315 to 380 nm), UV-B (280 to 315 nm), and UV-C (

Reactor-produced Hg-197 had previous medical use for imaging[1] but was discontinued due to low stability and low specific-activity. Cyclotron-produced Hg-197(m) can overcome the toxicity problem, due to much higher molar activity[2], allowing access to the radiometal’s useful decay modes (γ for SPECT-imaging. Conversion & auger electrons for therapy) at sub-toxic Hg-concentrations. Development in Hg ligands for medicinal applications necessitates stability in vivo but the poor long-term stability of Mercury compounds in solution is an ongoing issue[3]. Hg-organometallics show good water-stability and bypass the issue of Hg-S bonds suffering from competition by common biomolecules, e.g. cysteine. Therefore, our focus is on Hg-C chemistry, specifically the strongest bond kind: the mercury-phenyl bond[4]. As prior research has shown that the synthetically simpler route of monodentate ligands (κ1-L2Hg) suffers from significant cleavage[5], this research is centred on the syntheses of bidentate chelators benefitting from entropic stability. Purification of the Hg-197(m) leaves it in an acidic aqueous medium as the chloride salt, thus transmetallation, via stannyl or boronic acid derivatives, was chosen as a viable option for mercury attachment. Chelator designs began with a dibenzylisophthalamide template but low selectivity for the 1:1-compound encouraged a better fitting structure. Recent radio-labelling experiments show promise for specific binding with a design based on the bispidine backbone (attractive for being known in co-ordination chemistry for a variety of metals[6] and possessing bridge linking-functionalisation). Analyses are performed through radio-TLC and HPLC, whilst stable mercury compound analysis includes Hg-199 NMR. References : (1) Sodee. J. Nucl. Med. 1968; 9: 645. (2) Walther et al. Appl. Radiat. Isot. 2015; 97: 177–181. (3) Henke et al. Wat. Res. 2000; 34: 3005-3013. (4) Dean. Lange’s Handbook of Chemistry, 15th ed.; McGraw-Hill Inc, 1998; 606. (5) Wilhelm. et al. Z. Naturforsch. 2000; 55b: 35–38. (6) Comba et al. Inorg. Chem. 2009; 48: 6604–6614.

Positron emission tomography/computer tomography (PET/CT) is an established method in preclinical research in small animal disease models and the clinical diagnosis of cancer. It combines functional information of the positron-emitting biomarker with the anatomical data obtained from the CT image. Thus, it allows for 4D in vivo investigation of biological processes. Recently, PET/CT was used to monitor bone growth of chicken embryos using (18)F-fluoride as a bone-seeking tracer. We are interested in investigating the adequacy of additional PET/CT tracers in chicken embryos as an in vivo model system. For this reason, we evaluated several positron emitting compounds typically used in clinical tests or if these were not commercially available, we synthesised them. We studied the properties of these (18)F- and (68)Ga-labelled tracers and of (64)Cu-chloride in catheterised eggs via small animal microPET/CT. 2-Deoxy-2-[(18)F]fluoroglucose ([(18)F]FDG) was primarily absorbed at the sites of bone growth. (64)Cu chloride and a (68)Ga-labelled amyloid-fibril-binding antibody accumulated in the liver, while the (68)Ga-albumin desferrioxamine conjugate signal in liver decreased over time. These results indicate that these biomarkers can potentially be used for the monitoring of biological processes in chicken eggs as an animal model.

We report on the development of high-performance InAs/GaSb superlattice (SL) infrared (IR) detectors for the mid-wavelength (MWIR, 3–5 μm) and long-wavelength (LWIR, 8–12 μm) transmission window of the atmosphere. With a refined process technology, we are now able to fabricate dual-color focal plane arrays for the MWIR that excel at a very low number of noisy pixels. In an effort to correlate dark current and noise data of a larger number of devices, we found that for the description of the behavior in the white noise part of the spectrum, both, in InAs/GaSb SL photodiodes for the MWIR and the LWIR McIntyre’s well-known model for excess noise of avalanche photodiodes is, in general, much more suited than the commonly used shot noise model. The analysis of dark current contributions is a convenient method to identify limiting mechanisms and extract material parameters such as the minority carrier lifetime. We show that even in large area devices the contribution of the sidewall leakage path should not be ignored for this kind of investigation. Finally, we present our Al-free heterojunction device concept for reduced dark current.

The PET radionuclide (61)Cu is accessible through several nuclear reactions. Besides the common production route via (61)Ni(p,n)(61)Cu the (64)Zn(p,α)(61)Cu reaction offers some advantages. Especially the comparatively cheap enriched (64)Zn makes this process economical. For fast product purification and recycling of target material an ion exchange cascade was developed. In addition a separation technique with a copper selective resin was tested. (61)Cu with specific activities up to 1000 GBq/μmol was produced with these methods.

A removal, as far as possible, of the GaSb substrate is needed to optimize the quantum efficiency and the longevity, i.e., the maximum number of cool down cycles, of dual-colour InAs/GaSb superlattice focal plane array detectors for the mid-wavelength infrared atmospheric transmission window at 3-5 µm. For this purpose, three different vertical detector structures have been investigated and are compared in the present paper. A basic structure, comprising only the essential layers is evaluated against two more advanced structures, which include a lattice-matched InAsSb etch stop layer. For the basic structure the remaining substrate thickness amounts to roughly 20 µm. With a second structure, which employs an etch stop separated from the active diode structure by a sufficiently thick GaSb spacer layer, the substrate and the etch stop layer can be completely removed by combining mechanical lapping and polishing as well as different wet chemical etchants. Here, only epitaxially grown layers remain, but the spacer is still common to all pixels. A third structure combined with further optimized front- and backside processes is suited for the complete mechanical separation of dual-colour detector pixels in the focal plane array arrangement (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Bombesins (BN) containing (99m)Tc '4+1' complexes may be useful to detect tumors expressing the gastrin-releasing peptide receptor (GRPR). Derivatives of the formula [(99m)Tc(NS(3)R)(L2-BN(st))] were synthesized, in which Tc(III) is coordinated by an isocyanide L2-BN(st) bearing the peptide (BN(st)=βAla-βAla-Gln-Trp-Ala-Val-Gly-His-Cha-Nle-NH(2)) and a tetradentate chelator NS(3)R. NS(3)R consists of 2,2',2″-nitrilotriethanethiol (NS(3)) bearing a crown ether (NS(3)crown), an aliphatic amine (NS(3)en) and a tricarboxylic acid (NS(3)(COOH)(3)). Non-radioactive Re compounds were prepared and analysed by electrospray ionization mass spectrometry. The structural similarity to the (99m)Tc conjugates was demonstrated by their identical HPLC elution profiles. The lipophilicity of [(99m)Tc(NS(3)R)(L2-BN(st))] decreased depending on the coligands NS(3)crown (log D(O/W), pH=7.4, 0.98 ± 0.11), NS(3)en (-0.49 ± 0.07) and NS(3)(COOH)(3) (-2.01 ± 0.09). Biodistribution in normal rats was characterized by an increasing kidney uptake and a decreasing uptake into the liver corresponding to the reduced lipophilicity of the conjugates. The pancreatic uptake expressed by the organ/blood ratio of standardized uptake values at 60 min p.i. in rats was 8.6 ± 1.2 for [(99m)Tc(NS(3)en)(L2-BN(st))] and higher compared to the other conjugates. The pancreas/liver ratio of the SUV at 60 min p.i. in rats was highest for [(99m)Tc(NS(3)(COOH)(3))(L2-BN(st))] at 8.4 ± 1.3. [(99m)Tc(NS(3)en)(L2-BN(st))] was further studied in tumor-bearing mice and its pancreas/blood and pancreas/liver ratios were lower, however the pancreas/kidney ratios were higher in mice compared to rats. The activity uptake of [(99m)Tc(NS(3)en)(L2-BN(st))] into the PC-3 tumor xenografts was low (%ID/g: 0.83 ± 0.18 at 60 min; SUV: 0.21 ± 0.05 at 60 min) but specific.