Large band-edge Photocurrent Peak in thick methylammonium lead iodide photosensors with symmetric metal electrodes

This study examines the photocurrent (photoconductivity) spectra of thick methylammonium lead iodide perovskite layers coupled to symmetric metal electrodes. A large photocurrent peak has been observed in the near-band-gap wavelength region. The origin of this current peak is related to an interplay between the penetration depths of light having a certain wavelength and its ability to raise the concentration of the charge carriers. A model including the generation, position-specific or uniform recombination, as well as diffusion of charge carrier pairs, made it possible to reproduce the experimental findings. Besides the microscopic approach, we also present a phenomenological model and a simulation providing the conductance for an arbitrary relative orientation of the illuminating beam and the field imposed by the electrodes. The results enabled us to outline the functioning principle of a sensor for determining the angle of incidence of electromagnetic radiation. Furthermore, a method for estimating optical absorption spectra from photocurrent spectra is delineated

Topochemical copolymerization of fullerenes with cubane in their rotor-stator phases

A new family of heteromolecular crystals has been described recently: the rotor-stator phases of fullerenes with cubane. Cubane (C(8)H(8)), the stator component of these materials is a highly strained molecule which decomposes to higher stability C(8)H(8) hydrocarbons at 200 degrees C. This unimolecular isomerization takes also place in the rotor-stator phases, inducing a single phase topochemical reaction with the surrounding fullerenes. The resulting material is a random copolymer, percolating in the primitive cubic sublattices of the parent crystals. We followed the polymerization by HPLC, IR and UV-VIS spectroscopy, and determined the thermal stability by TG-MS analysis. The polymers are insoluble, and stable up to 400 degrees C. At this temperature they start to decompose while preserving their crystalline appearance. The influence of the side groups of substituted cubanes on the polymerization will also be discussed

The Antitumor Effect of Lipophilic Bisphosphonate BPH1222 in Melanoma Models: The Role of the PI3K/Akt Pathway and the Small G Protein Rheb

Malignant melanoma is one of the most metastatic cancer types, and despite recent success with novel treatment strategies, there is still a group of patients who do not respond to any therapies. Earlier, the prenylation inhibitor hydrophilic bisphosphonate zoledronic acid (ZA) was found to inhibit melanoma growth in vitro, but only a weaker effect was observed in vivo due to its hydrophilic properties. Recently, lipophilic bisphosphonates (such as BPH1222) were developed. Accordingly, for the first time, we compared the effect of BPH1222 to ZA in eight melanoma lines using viability, cell-cycle, clonogenic and spheroid assays, videomicroscopy, immunoblot, and xenograft experiments. Based on 2D and spheroid assays, the majority of cell lines were more sensitive to BPH. The activation of Akt and S6 proteins, but not Erk, was inhibited by BPH. Additionally, BPH had a stronger apoptotic effect than ZA, and the changes of Rheb showed a correlation with apoptosis. In vitro, only M24met cells were more sensitive to ZA than to BPH; however, in vivo growth of M24met was inhibited more strongly by BPH. Here, we present that lipophilic BPH is more effective on melanoma cells than ZA and identify the PI3K pathway, particularly Rheb as an important mediator of growth inhibition