Synthesis, characterization and density functional theory study of low cost hydrazone sensitizers

The 2-{4-[2-benzylidenehydrazino]phenyl}ethylene-1,1,2-tricarbonitrile (System 1), 2-{4-[2-(1-naphthylmethylene)hydrazino]phenyl}ethylene-1,1,2-tricarbonitrile (System 2) and 2-{4-[2-(9-anthrylmethylene)- hydrazino]phenyl}ethylene-1,1,2-tricarbonitrile (System 3) were synthesized by direct tricyanovinylation of hydrazones. The bathochromic shift in absorption spectra has been observed by increasing the solvent polarity. The FTIR spectra of these new dyes exhibited three important absorption bands. The first band centered near 3260 cm-1 in System 1 while 3208 cm-1 and 3211 cm-1 in System 2 and System 3 for the nNH absorption, respectively. The second band is a sharp absorption band in the region of 2212-2209 cm-1, which was attributed to the cyano group absorption. The third is an absorption band in the region of 1611-1603 cm-1 ascribed for the C=N. Density functional theory (DFT) calculation of relative energies, relative enthalpies and free energies shows that E isomers are the most stable except System 3 in which the most stable is Z isomers. The conformational energy profile shows two maxima near (-90 and 90o) while three local minima observed at (-180, 0 and 180) for N1-N2-C1-C2 torsional angle. The highest occupied molecular orbitals (HOMOs) are localized on the whole molecules while lowest unoccupied molecular orbitals (LUMOs) are distributed on the tricarbonitrile. KEY WORDS: Dye-sensitized solar cells, HOMO, LUMO, Absorption, FTIR spectra Bull. Chem. Soc. Ethiop. 2015, 29(1), 137-148DOI: http://dx.doi.org/10.4314/bcse.v29i1.1

High-pressure neutron study of the morphotropic PZT: phase transitions in a two-phase system

In piezoelectric ceramics the changes in the phase stabilities versus stress and temperature in the vicinity of the phase boundary play a central role. The present study was dedicated to the classical piezoelectric, lead-zirconate-titanate (PZT) ceramic with composition Pb(Zr$_{0.54}$Ti$_{0.46}$)O$_3$ at the Zr-rich side of the morphotropic phase boundary at which both intrinsic and extrinsic contributions to piezoelectricity are significant. The pressure-induced changes in this two-phase (rhombohedral $R3c$+monoclinic $Cm$ at room temperature and $R3c+P4mm$ above 1 GPa pressures) system were studied by high-pressure neutron powder diffraction technique. The experiments show that applying pressure favors the $R3c$ phase, whereas the $Cm$ phase transforms continuously to the $P4mm$, which is favored at elevated temperatures due to the competing entropy term. The $Cm\rightarrow R3c$ phase transformation is discontinuous. The transformation contributes to the extrinsic piezoelectricity. An important contribution to the intrinsic piezoelectricity was revealed: a large displacement of the $B$ cations (Zr and Ti) with respect to the oxygen anions is induced by pressure. Above 600 K a phase transition to a cubic phase took place. Balance between the competing terms dictates the curvature of the phase boundary. After high-pressure experiments the amount of rhombohedral phase was larger than initially, suggesting that on the Zr-rich side of the phase boundary the monoclinic phase is metastable.Comment: 6 figure

On carbon and oxygen isotope ratios in starburst galaxies: New data from NGC253 and Mrk231 and their implications

Using the IRAM 30-m telescope, CN and CO isotopologues have been measured toward the central regions of the nearby starburst galaxy NGC253 and the prototypical ultraluminous infrared galaxy Mrk231. In NGC253, the 12C/13C ratio is 40+-10. Assuming that the ratio also holds for the CO emitting gas, this yields 16O/18O = 145+-36 and 16O/17O = 1290+-365 and a 32S/34S ratio close to that measured for the local interstellar medium (20-25). No indication for vibrationally excited CN is found. Peak line intensity ratios between NGC253 and Mrk231 are ~100 for 12C16O and 12C18O J=1-0, while the ratio for 13C16O J=1-0 is ~250. This and similar 13CO and C18O line intensities in the J=1-0 and 2-1 transitions of Mrk231 suggest 12C/13C ~ 100 and 16O/18O ~ 100, in agreement with values obtained for the less evolved ultraluminous merger Arp220. Also accounting for other extragalactic data, 12C/13C ratios appear to vary over a full order of magnitude, from >100 in ultraluminous high redshift galaxies to ~100 in more local such galaxies to ~40 in weaker starbursts not undergoing a large scale merger to 25 in the Central Molecular Zone of the Milky Way. With 12C being predominantly synthesized in massive stars, while 13C is mostly ejected by longer lived lower mass stars at later times, this is qualitatively consistent with our results of decreasing carbon isotope ratios with time and rising metallicity. It is emphasized, however, that both infall of poorly processed material, initiating a nuclear starburst, as well as the ejecta from newly formed massive stars (in particular in case of a top-heavy stellar initial mass function) can raise the carbon isotope ratio for a limited amount of time.Comment: Accepted by Astronomy & Astrophysics, 6 figures, 4 table

Influence of Charge Transport Layers on Open Circuit Voltage and Hysteresis in Perovskite Solar Cells

Perovskite materials have experienced an impressive improvement in photovoltaic performance due to their unique combination of optoelectronic properties. Their remarkable progression, facilitated by the use of different device architectures, compositional engineering, and processing methodologies, contrasts with the lack of understanding of the materials properties and interface phenomena. Here we directly target the interplay between the charge-transporting layers (CTLs) and open-circuit potential (VOC) in the operation mechanism of the state-of-the-art CH3NH3PbI3 solar cells. Our results suggest that the VOC is controlled by the splitting of quasi-Fermi levels and recombination inside the perovskite, rather than being governed by any internal electric field established by the difference in the CTL work functions. In addition, we provide novel insights into the hysteretic origin in perovskite solar cells, identifying the nature of the contacts as a critical factor in defining the charge accumulation at its interface, leading to either ionic, electronic, or mixed ionic-electronic accumulation

How accurately can we predict the melting points of drug-like compounds?

© 2014 American Chemical Society. This article contributes a highly accurate model for predicting the melting points (MPs) of medicinal chemistry compounds. The model was developed using the largest published data set, comprising more than 47k compounds. The distributions of MPs in drug-like and drug lead sets showed that >90% of molecules melt within [50,250]°C. The final model calculated an RMSE of less than 33 °C for molecules from this temperature interval, which is the most important for medicinal chemistry users. This performance was achieved using a consensus model that performed calculations to a significantly higher accuracy than the individual models. We found that compounds with reactive and unstable groups were overrepresented among outlying compounds. These compounds could decompose during storage or measurement, thus introducing experimental errors. While filtering the data by removing outliers generally increased the accuracy of individual models, it did not significantly affect the results of the consensus models. Three analyzed distance to models did not allow us to flag molecules, which had MP values fell outside the applicability domain of the model. We believe that this negative result and the public availability of data from this article will encourage future studies to develop better approaches to define the applicability domain of models. The final model, MP data, and identified reactive groups are available online at http://ochem.eu/article/55638

36 GHz methanol lines from nearby galaxies: maser or quasi-thermal emission?

Methanol (CH3OH) is one of the most abundant interstellar molecules, offering a vast number of transitions to be studied, including many maser lines. While the strongest Galactic CH3OH lines, the so-called class II masers, show no indications for the presence of superluminous counterparts in external galaxies, the less luminous Galactic class I sources appear to be different. Here we report class I 36GHz CH3OH 4(-1) - 3(0) E line emission from the nearby galaxies Maffei2 and IC342, measured with the 100-m telescope at Effelsberg at three different epochs within a time span of about five weeks. The 36GHz methanol line of Maffei2 is the second most luminous among the sources detected with certainty outside the Local Group of galaxies. This is not matched by the moderate infrared luminosity of Maffei2. Higher resolution data are required to check whether this is related to its prominent bar and associated shocks. Upper limits for M82, NGC4388, NGC5728 and Arp220 are also presented. The previously reported detection of 36GHz maser emission in Arp220 is not confirmed. Non-detections are reported from the related class I 44GHz methanol transition towards Maffei2 and IC342, indicating that this line is not stronger than its 36GHz counterpart. In contrast to the previously detected 36GHz CH3OH emission in NGC253 and NGC4945, our 36GHz profiles towards Maffei2 and IC342 are similar to those of previously detected non-masing lines from other molecular species. However, by analogy to our Galactic center region, it may well be possible that the 36GHz methanol lines in Maffei~2 and IC~342 are composed of a large number of faint and narrow maser features that remain spatially unresolved. In view of this, a search for a weak broad 36GHz line component would also be desirable in NGC253 and NGC4945.Comment: Accepted by Astronomy & Astrophysics, 8 pages, 1 table, 3 figures, slight changes w.r.t. version 1 due to language editin

Diagnostic Imaging and Radiation Therapy in the Arab World: A New Model of Advanced Practice

This study aimed at suggesting a new model for advanced practice in the diagnostic imaging and radiation therapy in the Arab World by presenting a comparative study between the different medical imaging techniques, the concepts, benefits, risks and medical applications of these techniques has been presented with details. Attempting For building a new model of advanced practice for the diagnostic role of  imaging and radiation therapy in the Arab World; by analyzing the current status of the imaging and radiation therapy in the Arab World, and then surveying the different medical imaging techniques. Then  to suggest a model of best practices upon the outcomes of the study

Profiling estrogen, progesterone, and androgen receptors in colorectal cancer in relation to gender, menopausal status, clinical stage, and tumour sidedness

BackgroundAlthough estrogen (ERα/ERβ), progesterone (PGR), and androgen (AR) receptors are pathologically altered in colorectal cancer (CRC), their simultaneous expression within the same cohort of patients was not previously measured.MethodsERα/ERβ/PGR/AR proteins were measured in archived paired normal and malignant colon specimens (n =120 patients) by immunohistochemistry, and results were analyzed by gender, age (≤50 vs. ≥60 years), clinical stages (early-stage I/II vs. late-stage III/IV), and anatomical location (right; RSCs vs. left; LSCs). Effects of 17β-estradiol (E2), progesterone (P4), and testosterone alone or combined with the specific blockers of ERα (MPP dihydrochloride), ERβ (PHTPP), PGR (mifepristone), and AR (bicalutamide) on cell cycle and apoptosis were also measured in the SW480 male and HT29 female CRC cell lines. ResultsERα and AR proteins increased, whilst ERβ and PGR declined markedly in malignant specimens. Moreover, male neoplastic tissues showed highest AR expression, whilst ERβ and PGR weakest alongside ERα strongest expression was seen in cancerous tissues from women aged ≥60 years. Late-stage neoplasms also revealed maximal alterations in the expression of sex steroid receptors. By tumor location, LSCs disclosed significant elevations in ERα with marked declines in PGR compared with RSCs, and ERα strongest alongside PGR weakest expression was detected in advanced LSCs from women aged ≥60 years. Late-stage LSCs from females aged ≥60 years also showed weakest ERβ and strongest AR expression. In contrast, male RSC and LSC tissues exhibited equal ERβ and AR expression in all clinical stages. ERα and AR proteins also correlated positively, whereas ERβ and PGR inversely, with tumor characteristics. Concomitantly, E2 and P4 monotherapies triggered cell cycle arrest and apoptosis in the SW480 and HT29 cells, and while pre-treatment with ERα-blocker enhanced the effects of E2, ERβ-blocker and PGR-blocker suppressed the E2 and P4 anti-cancer actions, respectively. In contrast, treatment with the AR-blocker induced apoptosis, whilst co-treatment with testosterone hindered the effects. ConclusionsThis study advocates that protein expression of sex steroid receptors in malignant tissues could represent prognostic markers, as well as hormonal therapy could provide an alternative strategy against CRC, and their efficacies could be dependent on gender, clinical stage, and tumor location

Multi-Trait Diverse Germplasm Sources from Mini Core Collection for Sorghum Improvement

Sorghum is a multipurpose crop cultivated in over 100 countries, but its productivity is constrained by several biotic and abiotic stresses. Therefore, sorghum improvement programs largely focus on developing high-yielding cultivars with multiple traits including stress resistance, bioenergy and nutritional quality. This study was undertaken to meet breeders’ needs to develop such cultivars and identify diverse germplasm sources with multiple traits. The 242 sorghum mini core accessions were evaluated for agronomic traits (yield, maturity, 100-seed weight) in two post-rainy seasons under optimally irrigated and drought conditions and identified 21 accessions as a sources for agronomic traits. The evaluation of mini core revealed 70 accessions resistant to biotic stress, 12 to abiotic stress, 13 for bioenergy traits and 27 for nutritional traits. The 13,390 single nucleotide polymorphism markers on mini core were used to identify genetically diverse accessions with desirable agronomic traits: IS 23684 (nutrition traits, diseases, insect pests), IS 1212 (earliness, nutrition traits, drought, seedling vigor, diseases), IS 5094 (yield, drought, diseases, insect pests), IS 473 (earliness, diseases), IS 4698 (yield, Brix %, insect pests) and IS 23891 (greater seed weight, yield, Brix %, drought, diseases). These are useful genetic resources that meet breeders needs to develop agronomically superior sorghum cultivars with desirable combinations of multiple traits and a broad genetic base

Certified high-efficiency "large-area" perovskite solar cells module for Fresnel lens-based concentrated photovoltaic

This is the author accepted manuscript. The final version is available on open access from Cell Press via the DOI in this recordData availability: All data generated or analysed during this study are included in the Supplementary Information article and its data source. Source data are provided in this paper. All data reported in this paper will be shared by the lead contact upon request.The future of energy generation is well in tune with the critical needs of the global economy, leading to more green innovations and emissions-abatement technologies. Introducing concentrated photovoltaic (CPV) is one of the most promising technologies owing to its high photo-conversion efficiency (PCE). While most researchers use silicon and cadmium telluride for CPV, we investigate the potential in nascent technologies, such as perovskite solar cell (PSC). This work constitutes a preliminary investigation into a ‘large-area’ PSC module under a Fresnel lens (FL) with a ‘refractive optical concentrator-silicon-on-glass’ base to minimise the PV performance and scalability trade-off concerning the PSCs. The FL-PSC system measured the solar current-voltage characteristics in variable lens-to-cell distances and illuminations. A systematic study of the PSC module temperature was monitored using the COMSOL transient heat transfer mechanism. The FL-based technique for ‘large-area’ PSC architecture is an unfolded technology that further facilitates the potential for commercialisation.Engineering and Physical Sciences Research Council (EPSRC)Valais Energy Demonstrators FundEuropean Union Horizon 2020Deputyship for Research & Innovation, Ministry of Education, Saudi Arabi