Optimizing MRI sequences and images for MRI-based stereotactic radiosurgery treatment planning

AimDevelopment of MRI sequences and processing methods for the production of images appropriate for direct use in stereotactic radiosurgery (SRS) treatment planning.BackgroundMRI is useful in SRS treatment planning, especially for patients with brain lesions or anatomical targets that are poorly distinguished by CT, but its use requires further refinement. This methodology seeks to optimize MRI sequences to generate distortion-free and clinically relevant MR images for MRI-only SRS treatment planning.Materials and methodsWe used commercially available SRS MRI-guided radiotherapy phantoms and eight patients to optimize sequences for patient imaging. Workflow involved the choice of correct MRI sequence(s), optimization of the sequence parameters, evaluation of image quality (artifact free and clinically relevant), measurement of geometrical distortion, and evaluation of the accuracy of our offline correction algorithm.ResultsCT images showed a maximum deviation of 1.3 mm and minimum deviation of 0.4 mm from true fiducial position for SRS coordinate definition. Interestingly, uncorrected MR images showed maximum deviation of 1.2 mm and minimum of 0.4 mm, comparable to CT images used for SRS coordinate definition. After geometrical correction, we observed a maximum deviation of 1.1 mm and minimum deviation of only 0.3 mm.ConclusionOur optimized MRI pulse sequences and image correction technique show promising results; MR images produced under these conditions are appropriate for direct use in SRS treatment planning.     

Electron‐Beam‐Evaporated Nickel Oxide Hole Transport Layers for Perovskite‐Based Photovoltaics

High‐quality charge carrier transport materials are of key importance for stable and efficient perovskite‐based photovoltaics. This work reports on electron‐beam‐evaporated nickel oxide (NiO_x) layers, resulting in stable power conversion efficiencies (PCEs) of up to 18.5% when integrated into solar cells employing inkjet‐printed perovskite absorbers. By adding oxygen as a process gas and optimizing the layer thickness, transparent and efficient NiO_x hole transport layers (HTLs) are fabricated, exhibiting an average absorptance of only 1%. The versatility of the material is demonstrated for different absorber compositions and deposition techniques. As another highlight of this work, all‐evaporated perovskite solar cells employing an inorganic NiO_x HTL are presented, achieving stable PCEs of up to 15.4%. Along with good PCEs, devices with electron‐beam‐evaporated NiO_x show improved stability under realistic operating conditions with negligible degradation after 40 h of maximum power point tracking at 75 °C. Additionally, a strong improvement in device stability under ultraviolet radiation is found if compared to conventional perovskite solar cell architectures employing other metal oxide charge transport layers (e.g., titanium dioxide). Finally, an all‐evaporated perovskite solar mini‐module with a NiO_x HTL is presented, reaching a PCE of 12.4% on an active device area of 2.3 cm².     

Molecular phylogeny of the subterranean genus Niphargus (Crustacea: Amphipoda) in the Middle East: a comparison with European Niphargids

The subterranean genus Niphargus is one of the most species‐rich genera among freshwater amphipods in the world, distributed in the Western Palearctic. Thus far, taxonomic and phylogenetic research has focused mainly on the European half of the genus range. In this study, 25 populations of Niphargus from Iran, Lebanon and the Crimean Peninsula were investigated. Bayesian inference based on 28S, H3 and COI gene sequences suggests that populations from the area belong to four different clades. Three species from Crimea and one species from Iran are nested at basal nodes, indicating their rather ancient origin. The rest of the species are younger and belong to two separate clades. One Crimean species is a sister‐species to east Romanian species. The second clade includes one species from Lebanon and all but one population from Iran. The origin of this clade corresponds to marine transgression between the Black Sea and Mediterranean approximately 12 Mya. This clade was further investigated taxonomically. Revision of qualitative morphological traits and unilocus species delimitation methods using COI suggest that this clade comprises 12–16 species, of which only three have been described so far. Multilocus coalescence delimitation methods (using fragments of COI, 28S, H3 and ITS) strongly supported 11 of these species. The remaining populations comprise at least two species complexes that require further and more detailed taxonomic research. © 2015 The Linnean Society of London     

Flower ontogeny in Capparis spinosa (Capparaceae) with special emphasis on symmetry expression

The flower ontogeny of Capparis spinosa L. was studied using scanning electron microscopy (SEM) in order to shed light on the early expression of symmetry in a representative member of Capparaceae. Sepals start decussately with the abaxial and adaxial sepals, followed by the lateral ones. Petal appearance proceeds uni‐directionally from the abaxial to the adaxial side. Stamens develop centrifugally on an androecial ring. Five to seven carpel lobes arise on a gynoecial ring. Monosymmetry is established in early development by the uni‐directional petal appearance and is further enhanced by the acquisition of an abaxial nectary appendage and differential development of perianth organs at anthesis. The early monosymmetric pattern found in C. spinosa differs from the early monosymmetric and early disymmetric pathways of Cleomoideae. Our findings are consistent with the hypothesis that the late establishment of monosymmetry is a reflective of symmetry in early development.     

The stereoselective metabolism of halofantrine to desbutylhalofantrine in the rat: evidence of tissue-specific enantioselectivity in microsomal metabolism

The pharmacokinetics of the antimalarial drug (+/-)-halofantrine are stereoselective in humans and rats. To better understand the stereoselective metabolism of the drug to its primary metabolite, desbutylhalofantrine (DHF), a series of in vitro and in vivo experiments were undertaken in the rat. Formation of (-)-DHF exceeded that of (+)-DHF in liver microsomes [(-):(+) ratio of intrinsic formation clearances = 1.4]. In contrast, in intestinal microsomes no significant stereoselectivity was noted in the formation of the DHF enantiomers. Intestinal microsomes were also less efficient at producing the DHF enantiomers than were liver microsomes. Based on kinetic analysis of the DHF formation, there appeared to be more than one enzyme involved in the biotransformation. (+/-)-Ketoconazole (KTZ) effectively inhibited the formation of both DHF enantiomers by both liver and intestinal microsomes, although the reduction was more marked in liver microsomes. Through a combination of the use of CYP antibodies and recombinant CYP isoenzymes, the involvement of CYP 2B1/2, 3A1, 3A2, 1A1, 2C11, 2C6, 2D1, and 2D2 were implicated in the metabolism of halofantrine to DHF. Of these, CYP3A1/2 and CYP2C11 appeared to be the primary isoenzymes involved, although CYP2C11 showed greater (+)-DHF than (-)-DHF formation, whereas for CYP3A1 it was similar to the isolated rat liver microsomes. In vivo, oral (+/-)-KTZ caused significant increases in plasma halofantrine and decreases in DHF enantiomer plasma concentrations.     

Effect of Cation Composition on the Mechanical Stability of Perovskite Solar Cells

Photoactive perovskite semiconductors are highly tunable, with numerous inorganic and organic cations readily incorporated to modify optoelectronic properties. However, despite the importance of device reliability and long service lifetimes, the effects of various cations on the mechanical properties of perovskites are largely overlooked. In this study, the cohesion energy of perovskites containing various cation combinations of methylammonium, formamidinium, cesium, butylammonium, and 5‐aminovaleric acid is reported. A trade‐off is observed between the mechanical integrity and the efficiency of perovskite devices. High efficiency devices exhibit decreased cohesion, which is attributed to reduced grain sizes with the inclusion of additional cations and PbI₂ additives. Microindentation hardness testing is performed to estimate the fracture toughness of single‐crystal perovskite, and the results indicated perovskites are inherently fragile, even in the absence of grain boundaries and defects. The devices found to have the highest fracture energies are perovskites infiltrated into a porous TiO₂/ZrO₂/C triple layer, which provide extrinsic reinforcement and shielding for enhanced mechanical and chemical stability.     

Evaluation of the Role of Probiotics As a New Strategy to Eliminate Microbial Toxins: a Review

Probiotics and Antimicrobial Proteins - Probiotics are living microorganisms that have favorable effects on human and animal health. The most usual types of microorganisms recruited as probiotics...     

Physiological responses to cadmium stress in strawberry treated with pomegranate peel-activated carbon

Many reports have already been published regarding the removal of heavy metals from aqueous solutions onto activated carbon. However, the biosorbents' effect on the plant response still needs further investigation. In this study, activated carbon derived from the pomegranate peel [pomegranate activated carbons (PAC)] was used to see the effects of the addition of PAC on growing strawberry in Cd-contaminated sand. Cd accumulation and toxicity to strawberry was investigated by measuring the concentration of Cd in plant tissues and various biochemical activities of plant. Our results suggested that PAC had a high sorption capacity for Cd. Strawberry plant tried to deal with the Cd-induced oxidative stress by strengthening its antioxidant competences and decreasing Cd absorption. In comparison with the control, PAC applied to the sand decreased the level of lipid peroxidation and enhanced the carotenoid content. The greater tolerance of strawberry toward the level of Cd due to the application of PAC was associated with improving the physical conditions of the soil, increasing the amounts of some essential elements and decreasing the level of Cd absorption. Gaviota strawberry cultivar exposed to 5 or 10 mg kg^?1 Cd was able to adopt a new metabolic equilibrium, allowing the plant to cope with this metal.     

Pollination biology in Roepera (Zygophyllaceae): How flower structure and shape influence foraging activity

The foraging behavior of bees is a complex phenomenon that depends on numerous physical features of flowers. Of particular importance are accessibility of floral rewards, floral proportions, symmetry and orientation. The flowers of Roepera are characterized by the presence of staminal scales (SS), which play an important role in nectar protection. We studied two species of Roepera with different symmetry and flower orientation, which are mainly visited by honeybees (Apis mellifera). We aimed to show how the foraging behavior of honey bees is affected by the function of SS, floral symmetry and orientation. The foraging behavior was documented by video photography. Handling time, access to nectar, percentage of pollen/nectar foraging, percentage of pollen contact and pollen deposition site on the honey bee's body were assessed. The morphometric features of the honey bees and flowers were analyzed. We found that the SS restricted pollinator access to nectar. Our results indicated consistency of visitation patterns in zygomorphic, laterally oriented flowers of R. fuscata versus random patterns in actinomorphic, diversely oriented flowers of R. leptopetala. The relative proportions of SS and proboscis length appear to be crucial for the success of pollinators. The directionality of the honey bees' movement, together with the different positioning of reproductive organs, plays an important role in the accuracy of pollen transfer and pollination efficiency.