Formation of triple helical nanofibers using self-assembling chiral benzene-1,3,5-tricarboxamides and reversal of the nanostructure's handedness using mirror image building blocks

Intertwining triple helical nanofibers with an overall handedness have been formed from self-assembling chiral benzene-1,3,5-tricarboxamides 1, 2 and 3, whereas the achiralbenzene-1,3,5-tricarboxamide 4 upon self-association gives rise to straight nanofibers without any twist and transmission electron microscopy images of chiral compounds clearly demonstrate that the handedness of the triple helical nanofibers can be reversed by using the enantiomeric benzene-1,3,5-tricarboxamide building blocks.

Building integration photovoltaic module with reference to Ghana: using triple junction amorphous silicon

This paper assesses the potential for using building integrated photovoltaic (BIPV) roof shingles made from triple-junction amorphous silicon (3a-Si) for electrification and as a roofing material in tropical countries, such as Accra, Ghana. A model roof was constructed using triple-junction amorphous (3a-Si) PV on one section and conventional roofing tiles on the other. The performance of the PV module and tiles were measured, over a range of ambient temperatures and solar irradiance. PVSyst (a computer design software) was used to determine the most appropriate angle of tilt. It was observed that 3a-Si performs well in conditions such as Accra, because it is insensitive to high temperatures. Building integration gives security benefits, and reduces construction costs and embodied energy, compared to freestanding PV systems. Again, it serves as a means of protection from salt spray from the oceans and works well even when shaded. However, compared to conventional roofing materials, 3a-Si would increase the indoor temperature by 1-2 °C depending on the surface area of the roof covered with the PV modules. The results presented in this research enhance the understanding of varying factors involved in the selection of an appropriate method of PV installation to offset the short falls of the conventional roofing material in Ghana.

On the universal TRO of a JC*-triple, ideals and tensor products

In a development from material introduced in recent work, we discuss the interconnections between ternary rings of operators (TROs) and right C*-algebras generated by JC*-triples, deducing that every JC*-triple possesses a largest universally reversible ideal, that the universal TRO commutes with appropriate tensor products and establishing a reversibility criterion for type I JW*-triples.

Fractal geometry of aggregate snowflakes revealed by triple wavelength radar measurements

Radar reflectivity measurements from three different wavelengths are used to retrieve information about the shape of aggregate snowflakes in deep stratiform ice clouds. Dual-wavelength ratios are calculated for different shape models and compared to observations at 3, 35 and 94 GHz. It is demonstrated that many scattering models, including spherical and spheroidal models, do not adequately describe the aggregate snowflakes that are observed. The observations are consistent with fractal aggregate geometries generated by a physically-based aggregation model. It is demonstrated that the fractal dimension of large aggregates can be inferred directly from the radar data. Fractal dimensions close to 2 are retrieved, consistent with previous theoretical models and in-situ observations.

Triple isotope (δD, δ17O, δ18O) study on precipitation, drip water and speleothem fluid inclusions for a central European cave (NW Switzerland)

Deuterium (dD) and oxygen (d18O) isotopes are powerful tracers of the hydrological cycle and have been extensively used for paleoclimate reconstructions as they can provide information on past precipitation, temperature and atmospheric circulation. More recently, the use of 17Oexcess derived from precise measurement of d17O and d18O gives new and additional insights in tracing the hydrological cycle whereas uncertainties surround this proxy. However, 17Oexcess could provide additional information on the atmospheric conditions at the moisture source as well as about fractionations associated with transport and site processes. In this paper we trace water stable isotopes (dD, d17O and d18O) along their path from precipitation to cave drip water and finally to speleothem fluid inclusions for Milandre cave in northwestern Switzerland. A two year-long daily resolved precipitation isotope record close to the cave site is compared to collected cave drip water (3 months average resolution) and fluid inclusions of modern and Holocene stalagmites. Amount weighted mean dD, d18O and d17O are �71.0‰, �9.9‰, �5.2‰ for precipitation, �60.3‰, �8.7‰, �4.6‰ for cave drip water and �61.3‰, �8.3‰, �4.7‰ for recent fluid inclusions respectively. Second order parameters have also been derived in precipitation and drip water and present similar values with 18 per meg for 17Oexcess whereas d-excess is 1.5‰ more negative in drip water. Furthermore, the atmospheric signal is shifted towards enriched values in the drip water and fluid inclusions (D of ~ þ 10‰ for dD). The isotopic composition of cave drip water exhibits a weak seasonal signal which is shifted by around 8e10 months (groundwater residence time) when compared to the precipitation. Moreover, we carried out the first d17O measurement in speleothem fluid inclusions, as well as the first comparison of the d17O behaviour from the meteoric water to the fluid inclusions entrapment in speleothems. This study on precipitation, drip water and fluid inclusions will be used as a speleothem proxy calibration for Milandre cave in order to reconstruct paleotemperatures and moisture source variations for Western Central Europe.

Potential sites of triple-helical nucleic acid formation in chromosomes of Rhynchosciara (Diptera: Sciaridae) and Drosophila melanogaster

Antibodies to specific nucleic acid conformations are amongst the methods that have allowed the study of non-canonical (Watson-Crick) DNA structures in higher organisms. In this work, the structural limitations for the immunological detection of DNA.RNA hybrid duplexes were examined using specific RNA homopolymers as probes for homopolymer polydeoxyadenylic acid (poly(dA)).polydeoxythymidylic acid (poly(dT))-rich regions of Rhynchosciara americana (Diptera: Sciaridae) chromosomes. Anti-DNA.RNA duplexes did not react with the complex formed between chromosomal poly(dA) and exogenous polyuridylic acid (poly(rU)). Additionally, poly(rU) prevented the detection of polyadenylic acid.poly(dT) hybrid duplexes preformed in situ. These results raised the possibility that three-stranded structures rather than duplexes were formed in chromosomal sites. To test this hypothesis, the specificity of antibodies to triple-helical nucleic acids was reassessed employing distinct nucleic acid configurations. These antibodies were raised to the poly(dA).poly(rU).poly(rU) complex and have been used here for the first time in immunocytochemistry. Anti-triplex antibodies recognised the complex poly(dA).poly(rU).poly(rU) assembled with poly(rU) in poly(dA).poly(dT)-rich homopolymer regions of R. americana chromosomes. The antibodies could not detect short triplex stretches, suggesting the existence of constraints for triple-helix detection, probably related to triplex tract length. In addition, anti-poly(dA).poly(rU).poly(rU) antibodies reacted with the pericentric heterochromatin of RNase-treated polytene chromosomes of R. americana and Drosophila melanogaster. In apparent agreement with data obtained in cell types from other organisms, the results of this work suggest that significant triple-helix DNA extensions can be formed in pericentric regions of these species.

Triple- and quadruple-escape peaks in HPGe detectors: Experimental observation and Monte Carlo simulation

The triple- and quadruple-escape peaks of 6.128 MeV photons from the (19)F(p,alpha gamma)(16)O nuclear reaction were observed in an HPGe detector. The experimental peak areas, measured in spectra projected with a restriction function that allows quantitative comparison of data from different multiplicities, are in reasonably good agreement with those predicted by Monte Carlo simulations done with the general-purpose radiation-transport code PENELOPE. The behaviour of the escape intensities was simulated for some gamma-ray energies and detector dimensions; the results obtained can be extended to other energies using an empirical function and statistical properties related to the phenomenon. (C) 2010 Elsevier B.V. All rights reserved.

Magnetoresistance oscillations in triple quantum wells under microwave irradiation

The interference of magneto-intersubband oscillations and microwave-induced resistance oscillations is studied in high-density triple quantum wells. We give an introduction into magnetotransport in trilayer systems and focus on photoresistance measurements. The power and frequency dependence of the observed magnetoresistance oscillations can be described by the inelastic mechanism of photoresistance, generalized to the three-subband case. (C) 2009 Elsevier B.V. All rights reserved.

Magneto-intersubband oscillations in triple quantum wells

We present magnetotransport studies of high-density triple quantum well samples with different barrier widths. Because of electron transitions between three occupied 2D subbands, the magneto-resistance shows magneto-intersubband oscillations whose periodicity is determined by the subband separation energies. Temperature-dependent measurements allow us to extract quantum lifetime of electrons. A theoretical consideration of the observed phenomenon is also presented. (C) 2009 Elsevier B.V. All rights reserved.

Triple Structural Transition below Room Temperature in the Antifilarial Drug Diethylcarbamazine Citrate

A very unusual triple structural transition pattern below room temperature was observed for the antifilarial drug diethylcarbamazine citrate. Besides the first thermal, crystallographic, and vibrational investigations of this first-line drug used in clinical treatment for lymphatic filariasis, a noteworthy behavior with three structural transformations as a function of temperature was demonstrated by differential scanning calorimetry, Raman spectroscopy, and single-crystal X-ray diffractometry. Our X-ray data on single crystals allow for a complete featuring and understanding of all transitions, since the four structures associated with the three solid-solid phase transformations were accurately determined. Two of three structural transitions show an order-disorder mechanism and temperature hysteresis with exothermic peaks at 224 K (T(1)`) and 213 K (T(2)`) upon cooling and endothermic ones at 248 K (T(1)) and 226 K (T(2)) upon heating. The other transition occurs at 108 K (T(3)) and it is temperature-rate sensitive. Molecular displacements onto the (010) plane and conformational changes of the diethylcarbamazine backbone as a consequence of the C-H center dot center dot center dot N hydrogen bonding formation/cleavage between drug molecules explain the mechanism of the transitions at T(1)`/T(2). However, such changes are observed only on alternate columns of the drug intercalated by citrate chains, which leads to a doubling of the lattice period along the a axis of the 235 K structure with respect to the 150 and 293 K structures. At T(2)`/T(1), these structural alterations occur in all columns of the drug. At T(3), there is a rotation on the axis of the N-C bond between the carbamoyl moiety and an ethyl group of one crystallographically independent diethylcarbamazine molecule besides molecular shifts and other conformational alterations. The impact of this study is based on the fascinating finding in which the versatile capability of structural adaptation dependent on the thermal history was observed for a relatively simple organic salt, diethylcarbamazine citrate.