Spectroscopic, Viscositic and Molecular Modeling Studies on the Interaction of 3′-Azido-Daunorubicin Thiosemicarbazone with DNA

A new daunorubicin has been synthesized and structurally characterized. The interaction of native calf thymus DNA (ctDNA) with 3′-azido-daunorubicin thiosemicarbazone (ADNRT) was investigated under simulated physiological conditions by multi-spectroscopic techniques, viscometric measurements and molecular modeling study. It concluded that ADNRT could intercalate into the base pairs of ctDNA, and the fluorescence quenching by ctDNA was static quenching type. Thermodynamic parameters calculated suggested that the binding of ADNRT to ctDNA was mainly driven by hydrophobic interactions. The relative viscosity of ctDNA increased with the addition of ADNRT, which confirmed the intercalation mode. Furthermore, molecular modeling studies corroborate the above experimental results

Synthesis, optical and electrochemical characterization of anthrancene and benzothiadiazole-containing polyfluorene copolymers

New solution-processable, anthrancene- and benzothiadiazole-containing polyfluorene copolymers (P1-P3) have been synthesized and characterized. The preparation and characterization of the corresponding blue light-emitting devices are also reported. Polymers P2 and P3 show high photoluminescence efficiency while polymer P2 does not show any significant light emission up to 8.0 V. The results show the need for balance of electron and hole transport in polymer light emitting diodes. KEY WORDS: Anthracene, Benzothiadiazole, Polyfluorene copolymers, Photoluminescence, Light emitting diode  Bull. Chem. Soc. Ethiop. 2006, 20(2), 309-317

Significant Differences in Bacterial and Potentially Pathogenic Communities Between Sympatric Hooded Crane and Greater White-Fronted Goose

The gut microbiota of vertebrates play a crucial role in shaping the health of their hosts. However, knowledge of the avian intestinal microbiota has arguably lagged behind that of many other vertebrates. Here, we examine the intestinal bacterial communities of the hooded crane and the greater white-fronted goose at the Shengjin Lake of China, using high-throughput sequencing (Illumina Mi-Seq), and infer the potential pathogens associated with each species. Intestinal bacterial alpha-diversity in the greater white-fronted goose was significantly higher than that in hooded crane. The intestinal bacterial community compositions were significantly different between the two hosts, suggesting that host interactions with specific communities might have profound implications. In addition, potential pathogens were detected in both guts of the two hosts, suggesting that these wild birds might be at risk of disease and probably spread infectious disease to other sympatric vertebrates. The gut of hooded crane carried more potential pathogens than that of the greater white-fronted goose. The potentially pathogenic community compositions were also significantly different between the two hosts, suggesting the divergence of potentially pathogenic communities between hooded crane, and greater white-fronted goose. Finally, bacterial and potentially pathogenic structures showed strong evidence of phylogenic clustering in both hosts, further demonstrating that each host was associated with preferential and defined bacterial and potentially pathogenic communities. Our results argue that more attention should be paid to investigate avian intestinal pathogens which might increase disease risks for conspecifics and other mixed species, and even poultry and human beings

Immunomodulatory effect of Bifidobacterium breve on experimental allergic rhinitis in BALB/c mice

Bifidobacterium breve (B. breve) may have a beneficial effect on allergic rhinitis (AR). The aim of the present study was to investigate whether microbial induction of regulatory T cells (Tregs) and adjustment of Th1 and Th2 responses by B. breve are associated with protection against allergic inflammation, and to identify a dose-response association in a murine AR model. Ovalbumin (OVA)-sensitized BALB/c mice were orally treated with different doses of B. breve [10(10), 10(9), 10(7) and 10(5) colony forming units (CFU)]. Following nasal challenge with OVA, sneeze frequency, serum OVA-specific immunoglobulin E (IgE) and cytokine concentrations [interleukin (IL)-4, IL-10, IL-13 and interferon-gamma], splenic percentage of cluster of differentiation (CD)4+CD25+ Tregs, and morphology of the nasal mucosa were examined. Oral treatment with live B. breve at doses of 10(7) CFU or higher alleviated nasal mucosal injury and suppressed sneezing upon repeated administration over a 6-week period. Furthermore, treatment with B. breve at these higher doses reduced the concentrations of serum OVA-specific IgE, IL-4 and IL-10, and increased the splenic percentage of CD4+CD25+ Tregs in rhinitic mice compared with those who did not receive probiotics. In contrast, treatment with B. breve at a lower dose did not indicate any effect on sneezing frequency or mucosal morphology in this animal model, even though the splenic percentage of CD4+CD25+ Tregs increased and the concentrations of serum OVA-specific IgE and IL-10 declined. B. breve exerts its anti-allergic effects by inhibiting type 2 helper T cell immune responses and enhancing CD4+CD25+ Treg activity. Sneezing was also reduced at a dose of 10(7) CFU or higher. The current study investigated the role of B. breve and aided in identifying the optimal dose of B. breve administration in the treatment of AR

Line identification of extreme ultraviolet spectra from aluminum ions in EAST Tokamak plasmas

Extreme ultraviolet (EUV) spectra emitted from aluminum in the 5-340 A wavelength range were observed in Experimental Advanced Superconducting Tokamak (EAST) discharges. Several spectral lines from aluminum ions with different degrees of ionization were successfully observed with sufficient spectral intensities and resolutions using three fast-time-response EUV spectrometers. The line identification uses three independent state-of-art computational codes for the atomic structure calculations, which provide the wavelengths and radiative transition probabilities rate coefficients. These programs are HULLAC (Hebrew University - Lawrence Livermore Atomic Code), AUTOSTRUCTURE, and FAC (Flexible Atomic Code). Using three different codes allows us to resolve some ambiguities in identifying certain spectral lines and assess the validity of the theoretical predictions

In Situ Study the Dynamics of Blade-Coated All-Polymer Bulk Heterojunction Formation and Impact on Photovoltaic Performance of Solar Cells

All-polymer solar cells (all-PSCs) have achieved impressive progress by employing acceptors polymerized from well performing small-molecule non-fullerene acceptors. Herein, the device performance and morphology evolution in blade-coated all-PSCs based on PBDBT:PF5–Y5 blends prepared from two different solvents, chlorobenzene (CB), and ortho-xylene (o-XY) are studied. The absorption spectra in CB solution indicate more ordered conformation for PF5–Y5. The drying process of PBDBT:PF5–Y5 blends is monitored by in situ multifunctional spectroscopy and the final film morphology is characterized with ex situ techniques. Finer-mixed donor/acceptor nanostructures are obtained in CB-cast film than that in o-XY-cast ones, corresponding to more efficient charge generation in the solar cells. More importantly, the conformation of polymers in solution determines the overall film morphology and the device performance. The relatively more ordered structure in CB-cast films is beneficial for charge transport and reduced non-radiative energy loss. Therefore, to achieve high-performance all-PSCs with small energy loss, it is crucial to gain favorable aggregation in the initial stage in solution

A Facile Method to Enhance Photovoltaic Performance of Benzodithiophene-Isoindigo Polymers by Inserting Bithiophene Spacer

This study describes the synthesis and characterization of four polymers based on benzo[1,2-b:4,5-b']dithiophene (BDT) and isoindigo with zero, one, two, and three thiophene spacer groups. Results have demonstrated that the use of bithiophene as a spacer unit improves the geometry of the polymer chain, making it planar, and hence, potentially enhanced π- π stacking occurs. Due to favorable interaction of the polymer chains, enhanced absorption coefficient, and optimal morphology, PBDT-BTI, which possesses bithiophene as a spacer, revealed high current and fill factor leading to a power conversion efficiency of 7.3% in devices, making this polymer the best performing isoindigo-based material in polymer solar cells (PSCs). Also, PBDT-BTI could still maintain efficiency of over 6% with the active layer thickness of 270 nm, making it a potential candidate for a material in printed PSCs. These results demonstrate that the use of thiophene spacers in D-A polymers could be an important design strategy to produce high-performance PSCs